WowAce

Assistance for the Ra-den encounter. (Unstable Vita order, ball kill order)

Simple and rich Death Knight rune customizations

T_ItemInfo

Quest helping: fetching items to use, that sort of thing.

Embeddable chat throttling library with traffic shaping and priorities

Display the global cooldown around your cursor. (+ other stuff)

MultiTips

A helper addon for the achievements "Let It Snow", "Fistful of Love", "Shake Your Bunny-Maker", "Check Your Head", and "Turkey Lurkey"

Auto sizes frame layout depending on group/raid size or predefined zone data

Library to help with querying unit talents.

A superior broker/LDB display for users of the Recount damage-meter.

DotDotDot

Displays the time until the next battle and more.

A Data Broker plugin to show AddOn memory usage.

Raid Cooldowns

DeclineDuel

Adds a couple of graph displays to Skada.

PoisonMenu

Sanity2

Improved Quest Tracker