WowAce

Toggles WoW to the forground on events.

Shows ZoneInfo on the World Map in a perfectly cromulent fashion.

Easily mail friends, guild members, alts and others

You've got mail!

Does stuff for sachmo

Litmus

Attach diminishing return icons to unit frames.

A simplistic clock.

Tracks skill and tradeskill costs and progressions, as well as trainer locations.

Proximo

Tracks SendAddonMessage Spam

Creates virtual cyphered chat channels over guild addon communication channel.

Database of Vendor locations for HandyNotes

Niagara

Monitors for friendly deaths and announces them as in Myth: The Fallen Lords

Personal buff monitor - are you buff enough?

Mutt (Macro Update Target Tool) provides slash-commands that can patch the predefined targets in your macros.

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

LittleTrouble

Replacement for default Rune Frame and more.