WowAce

Instant PROC notification

A Perl layout with oUF.

Adds on-screen buttons for the farming tools and seeds.

Reminds you if your flask/elixir and/or Augmentation Rune and/orfood buff is about to expire or has expired

Handles the assignment, coordination, and announcement of many parts of the Lich King encounter in Icecrown Citadel.

Simple and clean Death Knight displays

TradeStop

BigTrouble

ArenaPointer

ActionCombat

Spyglass

On login, displays changes to your guild since the last time you logged in.

Should I send that recipe to my alt?

Automatically sells low quality gray items and selected white items to the vendor.

Helps you automate selling stuff.

Nudge

Adds Friend and Guild options to the context menu of player units.

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

Enables the filtering of items when you visit a vendor

Adds four icon indicators to Grid (top, bottom, left and right).