WowAce

Keeps track of current money and all your characters on one realm.

Desesperated announcing to clearly show the skillings of act inplay.

View bank, inventory, mail, equipped and guild bank contents from any character anywhere!

Litmus

Smart mount randomization on a button! Empty coconut halves not included.

Cleans up minimap buttons and makes them accessible through a pop out menu!

Easily mail friends, guild members, alts and others

Shows mana usage as a percentage in a spells tooltip.

Does stuff for sachmo

CraftList2

Attach diminishing return icons to unit frames.

A Friend-Enemy-Unit-Frame for battlegrounds.

You've got mail!

Threat reactive nameplates for TidyPlates.

Says random things in chat when casting any spell or ability. Type "/ss help" for the user's manual.

Heads Up Display with Player and Target Info

OneBank3 will combine all the bank bags into one frame.

An auction house AddOn to make the life of each fence easier.

Some handy events that should exist in the default UI

Provides quick access to information on your group and their equipment, enchant and gem choices.