WowAce

Displays online friends.

Swiss Army knife for instances, including player tracking, ignore buttons, loot tracking, notes, and more.

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

Depot

Provides the ability to suppress specific spellcasts like "Deaden" from your casting bars.

FuBar_tTracker

ColaLight

Allows customisation of login/logout system messages.

TradeStop

MiniChat

Displays the time until the next battle and more.

FuBar_PoisonReminderFu

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

GearRating

Control screenshot format and quality via LDB displays

Libary for cleanly inspecting other players

SmartQueue

SanityItemCache

A Library for stat conversion, calculation and summarization.

Note + rep tracking for players, with guild data sharing.