A Bigger Bag adds tooltip information to any relevant NPC in Pandaria:
Which achievement-related items drop
Which other NPCs drop the same item
Whether you've collected that item before
1.1: Updated GUID format for patch 6.0.
1.0e: Better fix for the prior fix, I'll learn one of these days.
1.0d: Better fix for the prior bug, I'll learn one of these days.
1.0c: Fixed a bug where pet battles could cause Lua errors.
1.0b: Fixed a bug where dying units could cause Lua errors.
1.0a: Fixed a bug where ABB would fail to detect collection of items with dashes in their names.