WowAce

Reports in raid chat whenever a raid member "fails." /EnsidiaFails to configure.

Buffalo

ShadowGreenLight helps you decide if recasting SWP/Corruption is worthwhile

Tracks vulnerability debuffs on multiple mobs

Highly-configurable shield / absorb tracker.

Detects specific CDs and spellcasts

Aura alarm.

A Small movable frame that shows who in your party has your Renewing Mist buff

Disease Tracker for Death Knights.

A small checklist for raid (de)buffs and who brings what.

AceBuffGroups

Keeps track of HoTs, DoTs, Buffs and Cooldowns. With audio and text alerts to refresh them.

Piece of mind by being one with your class.

Instant SLAM! notification

Target Debuff monitor. Stacking aware, giving current and potential debuff status.

Instant PROC notification

Test whether the player can really dispell a buff or debuff, given its talents.

Tells you if you're buffed

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

Visual Raid Cooldown Tracking