WowAce

trade history log, recent trade list by [email protected]

Raid Inviter

PowerPoint goodness for your addon

Uses TomTom to show target location if target is in party or raid.

Checklist2

Shows the spec of people around you in the tooltip.

Aggro Warning System for Parties and Raids.

NCHide

Shift-clicking on a user name in chat shows a tooltip with their whois information.

PvP plugin for any DataBroker display.

Pet Battle Lite Frame

Suppress chat messages when specified items are looted

ArenaHistory

User-configurable protection for your inventory. Automatically buys back mistakenly sold items.

Shows guild and system message of the day only if either one of them has changed since the last login.

BetterOutbox

Auto-target your Prospector/Milling/Enchanting skills. v1.18

WoWonid

Notifies you of new calendar event invites and reminds of upcoming events on all characters and realms

Add-on that shows in a unit tooltip window a number of killed mobs of the same kind