WowAce

Provides accurate, millisecond-level timing.

Nostalgia

Movable frame library.

Keeps track of your reagents.

With Mists of Pandaria Blizzard publish all characters from an account unless you disable that 'feature'. This addon warns you.

Makes clicking the shields during the Atramedes encounter spammable

Broker_CalendarEvents

Guide Handler UI.

TagCompiler-1.0

Combat log analysis

Provides search functionality to the chatframes

YellCollect

DKPmon_eqDKP

Adds aggro coloring to oUF.

Adds spell-based range checking to Grid, and the ability to check multiple ranges.

Adds dungeon role icons to Grid2

Lightweight line-based info-display frame

Enables the setup of the Shaman "Call of" spells

Makes you elite

FuBar2