ncSpellalert is an addon for alerting you when an enemy casts an interuptable or important spell, your enemy gains an important buff or an enemy drinks/trinkets. This addon is based on evl_Spellalert so a lot of credit for evl. Please give feedback and tell me if I need to add/remove certain spells to the proc list.
Download & go! To change/add/delete spells that it should notify, open config.lua with your favorite plain text editor and start editing! By default this addon is only enabled in PvP zones, to show it in all zones set "pvponly" to false in config.lua. Also, by default this addon messages for all units when they cast important spells or get important buffs, but you can also make it alert for only a few units by setting "allunits" to false in config.lua and changing "units" to your wishes(defaults to target and focus only).
Updated for 4.1
Added more abilities to the list
Updated spell IDs for 4.0, and added in more spells/abilities