WowAce

Spell overlay customization and spell state HUD.

A raid buff tracker

Adds aura indicators to unit frames

Customizing your buff display

DebuffEnough

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

Calculates incoming damage avoidance and mitigation

MoBuffs

Allows combined aura detection. motw + gotw, all 4 mage int buffs, etc. in one status.

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

Bars showing amount of buffstacks

EBB-inspired buff bars with click-to-remove support

Shows at-a-glance what raid buffs/debuffs you have.

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

Audible Alerts for self-gain, self-lost, any-gain, all-lost of statuses.

Automagically call who should cross over

Shows a countdown bar for the duration of auras (e.g. HoTs, DoTs)

Provides training reminders to help decipher the Blizzard Spell Alerts.

Adds Buff/Debuff icons to the grid frame.

Keeps track of important de-/buffs in a splash screen