WowAce

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

A popup menu containing user-programmable scripts.

SmartyCatManaBar

PerfectTargets

Hitman

Allows you to create icons, which can be customized greatly by user's input. CiR is more than just the usual cooldown tracker.

Provide plenty of links

Clean looking square minimap with many options.

Adds a couple of graph displays to Skada.

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

SmartyCat

MobHealth

Library to help with querying unit talents.

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

Displays an alert whenever you loot an item for the first time.

This will keep track of how much you have paid per item in your inventory. Only one of (Auctionator, Auctioneer, AuctionLite,...

Generates and posts random Chuck Norris facts to a specified chat medium.

Add-on that shows which battle pets can be farmed this week

Displays online guild mates.

Pet Theory