WowAce

adds navigation buttons to Encounter Journal

PT3Bar

Automates bites during the Blood-Queen Lana'thel encounter in Icecrown Citadel

A library to return spell duration and debuff type of a spellID.

GDKP gold run ledger

Swiss Army knife for instances, including player tracking, ignore buttons, loot tracking, notes, and more.

Uses guild notes to add alts' main names to chat windows and other places

OneBag is a replacement for the default game bags that combines all the bags into one frame.

Resizes some default UI frames (GuildUI, LootFrame, RaidInfo, TradeSkillUI and TrainerUI) to show more lines

Shows activity for hidden ChatFrames by making their tabs flash.

JasonQuest

Adds two icon indicators to each corner (total: 8 icon indicators).

Displays the zone level ranage of the zone you are in and also gives you a suggest zone and instances to be in.

Scorchio!

BeneCast 10

eeShards

Allows customisation of login/logout system messages.

Buffalo2

FruityLoots

CharScanner scans Basic Character Data, Talent Specifications, Equipment, PvE/PvP Achievements, PvE Boss Kill Statistics and ...