WowAce

JostleLib

Allows communication to be shared across realm through Battle.net.

aUF_Banzai

Adds an additional spell alert if you have more than one charge of a buff that is normally tracked by the in game spell alert...

Helps with interrupt notifications and announcements.

Adds easier gear switching to FuBar.

Pet Battle Lite Frame

LD50_ap

NielasAran

Automatically converts a party to a raid when you attempt to zone into a raid zone without a raid.

Shows at-a-glance what raid buffs/debuffs you have.

Displays both Kalecgos and Sathrovarr the Corruptor hit points during the encounter.

One Click Forced Exit / Logout / Reload UI button for Broker

LibGUIFactory-1.0

Displays how much total honor you have from all sources.

ArenaHistory

Echos quest objective completion to your party

CleanShot

Provides a library for accessing auction data and pricing from various Auction Data mods

Uses linear regression and a log of hitpoint values to estimate how long a boss has left to die and reach execute range.