The change log lists changes of particular note to users, not every change made.

v0.48
- Suggestions Tab: Zone/instance and subzone override options added. Use them to see suggestions for locations far and near without actually traveling there!
- "Check Your Head": Fixed an issue where some races were associated with the wrong criteria.

v0.47
- "Check Your Head": Option added to show whether you need to use a Weighted Jack-o'-Lantern on players in their tooltips.
- Suggestions Tab: Implemented proper differentiation between 10- and 25-man raid achievements and proper detection of whether the player is in a Heroic instance, whether it is a 10- or 25-man raid instance, and (when not in an instance) the current raid/dungeon difficulty settings.
- Suggestions Tab: Many new suggestions added: Ulduar, Icecrown's Argent Tournament, Isle of Conquest, Onyxia's Lair (level 80 version), and more.
- Kill Creature Achievements: Now only shows a reminder if the player can attack the unit. This prevents reminders to destroy certain siege weapons (which can be either friendly or hostile) while they are friendly, for example.
- The option to not play a reminder sound for fishing node reminders if a fishing pole is equipped no longer affects whether achievements are added to the list of recent reminders.
- "Show achievement IDs" option now affects tooltips in the main achievement UI.

v0.46
- Timed achievements are now added to the Suggestions list when the timer starts.
- Achievements added in WoW 3.2 are now included in search results.
- Suggestions Tab: Fixed an error that occurred when looking at Suggestions while in Wintergrasp.

v0.45
- Updated for WoW patch 3.2.
- Suggestions Tab: Now only displays "The Fishing Diplomat" when appropriate for your current location as determined by whether the relevant criteria is complete and the current filter ("Earned"/"Incomplete"/"All"). For instance, if you are in Stormwind and the "Stormwind" criteria is complete, "The Fishing Diplomat" is only suggested when the filter is set to "All" or "Earned."
- Trade module: Fixed an issue where, with English clients, Worm Delight wasn't considered a requirement of "The Northrend Gourmet" because WoW lists it as "Wyrm Delight" in the achievement itself.

v0.44
- "It's Happy Hour Somewhere" and "Tastes Like Chicken": Implemented a system to work around the fact that, since WoW 3.1, addons cannot use Blizzard's API to query whether a specific item has already been consumed. The new system tracks whether items have been consumed itself and stores this on a per-character basis. The primary drawback to this is that all items are labeled as unconsumed until Overachiever v0.44+ "sees" you consume them (even if you consumed them before). (Additionally, in the rare event of a rollback, items may be marked as consumed when the character hasn't actually consumed them.)
- Trade module: Fixed an issue where, with English clients, "The Northrend Gourmet" didn't consider Rhinolicious Wormsteak as a requirement because WoW lists it as "Rhinolicious Wyrmsteak" in the achievement itself.
- Suggestions Tab: The Horde-specific versions of "Destruction Derby" and "Master of Wintergrasp" are now suggested to Horde players in Wintergrasp instead of the Alliance versions.

v0.43
- Added an option to display whether you need to kill a creature for an achievement in its tooltip. This applies not only to such achievements as "Northern Exposure" and "Medium Rare," but many others. See the option's tooltip in-game for more information.
- enGB clients: Fixed an issue where the completion date shown when comparing your progress with another's in an achievement link appeared in the enUS format instead of dd/mm/yy.

v0.42
- "Shake Your Bunny-Maker": Players of an unknown level ("skulls") are now assumed to be at least level 18. (While this won't always be the case, it's worth the assumption most of the time.)

v0.41
- "Shake Your Bunny-Maker": Option added to show whether you need to use Spring Flowers on players in their tooltips.
- Unit tooltips can now show multiple reminders when applicable.
- Tabs module: Achievement filters ("Earned"/"Incomplete"/"All") for each tab in the main UI are now saved between sessions (including the default tab).
- Tabs module: Fixed a display glitch that occurred when switching to an Overachiever tab if the previous tab's categories list was long enough to be scrollable.
- Fixed an issue that caused the client to lock up if the Objectives frame was used to attempt to open the UI to an achievement that is exclusive to the opposing faction.
- Trade module: Fixed an issue where, with English clients, "The Northrend Gourmet" didn't consider Spiced Worm Burger as a requirement because it is incorrectly listed as "Spiced Wyrm Burger" in the achievement itself by Blizzard. A system is now in place to allow translators to make these name substitutions for cooking achievements' criteria. (See the context notes for the TRADE_COOKING_OBJRENAME phrase in the Curse Forge localization system.)
- Mexican localization (esMX) is now supported. It falls back on Spanish (esES) translations when esMX-specific ones are unavailable.
- All localizations are now supported in the base code, though not all have translations. Please help contribute if you are able: http://wow.curseforge.com/projects/overachiever/localization/

v0.40
- Updated for WoW patch 3.1.
- Options involving the now-defunct achievement tracker have been removed. The default UI's new Objectives frame (AKA Watch Frame) has taken its place, and it is draggable.
- The remaining features that involved some interaction with the old tracker's icons are now associated with the achievement titles displayed by the Objectives frame (since the new frame does not use achievement icons). This includes achievement tooltip display and Shift+clicking to produce chat links.
- Watch Tab: You can now Alt+click on an achievement's chat link to watch it.

v0.39
- Tabs module: The new Watch tab has been implemented, allowing you to create a custom list of achievements. Alt+click on an achievement in another tab to watch it. Alt+click on an achievement in the Watch tab to stop watching it.

v0.38
- New option: Auto-track timed achievements.
- The exploration auto-tracking option will no longer cause tracking to switch away from "Bloody Rare," "Northern Exposure," or their followup achievements.

v0.37
- Tabs module: You can now use the dropdown added to the default UI in WoW 3.0.8 to filter Search results and Suggestions. The Suggestions filter defaults to "Incomplete"; by changing it, you can now display achievements that you've already earned.
- Suggestions Tab: Added battleground achievements.
- Suggestions Tab: Added Cooking and Fishing achievements. When the Cooking tradeskill window is open, all suggestions will be for Cooking. Otherwise, if a fishing pole is equipped, all suggestions will be for Fishing. In other cases, Cooking and Fishing achievements specific to the zone you're in will be shown alongside other relevant achievements.

v0.36
- Trade module: Now supports lilsparky's branch of Skillet. Because that addon uses ctrl-clicking on recipes to do something else, use Alt instead to open to the achievement associated with the recipe.
- Fixed an issue that occurred when using a client that isn't updated to WoW 3.0.8 yet (Chinese).
- Revamped the localization system.

v0.35
- Trade module: You can now ctrl-click on a recipe in the list to open the achievement UI to the achievement for which you still need to cook the recipe.
- Trade module: Now supports the addon Advanced Trade Skill Window.
- Suggestions Tabs: Added several new zone-based suggestions.
- Fixed various situational bugs.

v0.34
- Trade module: Now supports the addon Skillet. Achievement icons are placed before the names of recipes you need to cook in the main list. Tooltips and text beneath the selected recipe's reagents list indicate which achievements are associated with the recipe.
- Extra feature for Skillet users: A new sorting method, "By Achievement," is provided. This sorts the list of recipes by the number of achievements the recipe is associated with (provided you haven't already cooked the given recipe), then by the name of the first such achievement (which is "first" is determined by ID, though currently there is no overlap between relevant achievements), and finally, by the recipe name.
- Trade module: Fixed an error that occurs with non-English clients.
- Updated German localization.

v0.33
- "The Northrend Gourmet" and "The Outland Gourmet": Pulled this functionality out of the core addon and placed it into a new module, Overachiever_Trade. The module may be disabled or deleted if desired.
- The new module is far more efficient and accurate than the old system and fixes an issue where the reminder icon system didn't always initialize properly (which resulted in no icons appearing in the trade skill UI).
- Updated most localizations.

v0.32
- "Pest Control" (new): Added an option to display reminder tooltips for critters you need to kill.
- "To All The Squirrels Who Shared My Life" (new): Critters' /loved status for this achievement is now part of the option that exists for "To All The Squirrels I've Loved Before."
- "The Northrend Gourmet" and "The Outland Gourmet" (new): In the trade skill UI, an achievement shield icon is now placed next to recipes that you currently need to cook in order to earn these achievements. A tooltip indicates which achievement requires the given recipe.
- Added an option to display a tooltip when the cursor is over an achievement in the main achievement UI giving the names of any meta-achievements that list this achievement as a criteria.
- Changed achievement sorting so that two strings beginning with numbers compare the numbers first. This means "5 Exalted Reputations" is now listed before "20 Exalted Reputations," for example.
- Updated most localizations. Translations are generously provided by users like you! Please help contribute if you are able: http://wow.curseforge.com/projects/overachiever/localization/

v0.31
- Suggestions Tab: Many new suggestions based on your current location are possible, including those for: completing a number of quests in your zone, goals to accomplish in your current dungeon or raid instance (or, in some cases, one you are near), Heroic dungeon or raid goals when that is the current difficulty mode, City PvP goals when in a capitol city (varying, depending on your faction and which city it is), Wintergrasp PvP, and more.
- Suggestions Tab: Achievements you were reminded about through a tooltip within the last 2 minutes are now given as suggestions. Additionally, any such achievement in any Overachiever-provided tab has its background colored green for quick identification.
- "It's Happy Hour Somewhere" and "Tastes Like Chicken": Now examines item IDs instead of names, making this option more reliable.
- If draggable frames with saved positions are used and you log in with a character that doesn't have a position saved for one of these frames yet, the position used by the previous character is applied. (Positions are still saved per character, so each one can have a different layout if desired. This simply removes the need for dragging frames to the same location every time you log in with a new character.)
- Format of the completion date shown when comparing your progress with another's in an achievement link changed to dd/mm/yy for enGB and non-English clients.
- Fixed an issue where the achievement frame wouldn't save its position if the achievement UI loaded earlier than normal (as another addon may cause to be the case).
- "Let It Snow" and "Fistful of Love": Reminders should now trigger properly with non-English clients.
- Spanish localization updated.

v0.30
- Added an option to display a tooltip when the cursor is over an achievement in the main achievement UI that is part of a series in order to display the names of other achievements in the series and its relation to them.
- The Overachiever Tabs module has been released! This adds two new tabs to the default achievement UI. This module is installed as a separate addon: The Overachiever_Tabs folder goes in the AddOns folder along with the Overachiever folder. The module can be disabled or you can opt to not install it without affecting the core addon's functionality.
- The first new tab is Search. Use it to search for achievements by name, description, criteria, and/or reward. You can opt to only display achievements available in the normal UI or to include all achievements, including those exclusive to the opposing faction, etc.
- The second new tab is Suggestions. This is where Overachiever will display achievements you might be interested in based on your character's current circumstances. For now, it simply displays incomplete exploration achievements for the current zone, but more is planned for the future.
- Key bindings have been added to open to the Search and Suggestions tabs. Set them in the default key bindings interface.
- Individual tabs can be disabled without disabling the entire Tabs module by renaming or deleting the individual file that creates that tab. That'd be either Search.lua or Suggestions.lua.
- Compensated for a Blizzard typo that made Tel'Abim Bananas get overlooked by the "Tastes Like Chicken" check when using an English client.
- Spanish localization implemented. (Some unresolved issues remain. Please report any you find.)
- Updated German localization.

v0.25
- Updated localizations: French, traditional Chinese.

v0.24
- New option for "It's Happy Hour Somewhere" and "Tastes Like Chicken": Show whether an item needs to be consumed in its tooltip. A second new option has this display even when the achievement is complete (for the curious).
- New option added to choose a sound effect to play when reminder text is added to the tooltip about an incomplete achievement. It will not play more than once every 15 seconds. This uses LibSharedMedia, so any sound registered with that library can be selected. (No sound selected by default.)
- New option added to prevent the reminder sound from being triggered by fishing nodes when your fishing pole is equipped. (Enabled by default.)
- Fixed a compatibility issue that produced an error when some addons made the tooltip show before Overachiever was fully initialized.
- Simplified Chinese localization implemented.

v0.23
- When you enable an exploration achievement auto-tracking option, tracking begins immediately (if applicable) instead of requiring you to enter a new zone.
- Slash commands /oa, /oasilent, and /oas now show Overachiever's interface options instead of the main achievement UI when no argument is provided.
- Updated to latest LibBabble-Zone-3.0 (used for auto-tracking of exploration zones).

v0.22
- Fixed an issue that could cause taint if the draggable achievement tracker is enabled when performing certain actions while in combat, such as entering/exiting a vehicle.
- Updated localizations: German, traditional Chinese.

v0.21
- "Let It Snow" and "Fistful of Love" achievements: Options added to show whether you need to use a Handful of Snowflakes or a Handful of Rose Petals on players in their tooltips.
- Traditional Chinese and Russian localizations updated.

v0.20
- "Well Read" achievement option expanded to include "Higher Learning."
- New option: Show in fishing nodes' tooltips whether you need to fish them for "The Scavenger," "Outland Angler," or "Northrend Angler."
- Fixed an error that occurred when trying to open to an achievement that isn't in the normal UI. (For example, achievements exclusive to the opposing faction.)
- Russian localization implemented.

v0.18
- New option for "Well Read" achievement: Add whether you've read a relevant book to its tooltip.

v0.17
- The achievement tracker is now draggable.
- Traditional Chinese localization implemented.

v0.16
- Quantity-based criteria progress is now added to the tooltip even if it is of the type that would not use a progress bar when it is tracked, including information that is normally hidden from the user.
- When there are multiple criteria, your progress with each is now inserted directly next to its listing on the achievement tooltip. (Combined with the above change, you might see something like this: "Assault 2 bases (0/2).")
- Achievement progress comparison feature added, replacing the option to simply show your "progress bar data" in others' achievement links.

v0.15
- Revamped automatic tracking of exploration achievements to better support non-English clients.
- French localization implemented.

v0.14
- New option added to save the position of the draggable Achievement UI.
- Corrected German localization issue. Further work may be necessary, but this should be an improvement.

v0.13
- German localization implemented.

v0.12
- The main Achievement UI is now draggable.

v0.11
- Initial release.

Buy Tuhljin a snack so he'll feel guilty about not yet implementing that suggestion you made. Or maybe just to show your support. That works, too.