WowAce

Shared handling of media data (fonts, sounds, textures, ...) between addons.

Raid level alternative player power warning (Atramedes, Cho'gall, Lord Rhyolith)

Simple font replacement

Right-click on minimap blips to open a targeting menu (out of combat).

FuBar_AlchemyFu

Simple, nice-looking power bar addon for all classes.

ShadowGreenLight helps you decide if recasting SWP/Corruption is worthwhile

DarkCandy

Shows the price of a single item in the Auction House.

A simplistic clock.

Adds a Friendly Fire mode and data collection to Skada.

iTargetingFrames

opens/closes all bags when at merchant (instead of only the backpack)

Gives a score for your kit allowing easy comparison with others, also colour codes kit based on appropriateness for your level.

MiniPet, Always keep your little companion with you, based on the work of Carra.

T_ItemInfo

Tooltip scanning library.

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

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

NCHide