WowAce

Adds a cooldown timer for Nezir's Ice Patch ability.

Manage your AddOns while logged into the game

Displays the remaining time on grid icon's cooldown animation.

Really very early stage. No, earlier than that.

Simple embeddable publish-subscribe implementation.

Mute all sounds except boss emotes and addon sounds

Grid status module that shows the remaining value of any effect tracked by AbsorbsMonitor

A texture browser for developers and UI modders

Uses Loot-a-Rang on double right click

LibAvionOptions-2.0

OneBank

End of combat reporting for feedback on how your cast time was spent or wasted.

Meant To Do That

RC4Lib

Blocks all whispers except from people in your guild and friends list.

Synchronise friends among your characters

Add in keybindings to place raid marks on mouseover, or the target if there is no unit being moused over

Addon for priority management of combat skills for all classes

Adds Statuses for group: leader / assistant / master looter.

Tells your party members when you interrupt stuff, or fail to do so.