WowAce

Drop the cheapest thing you're carrying

Lightweight but powerful auction house interface

Complete tradeskill information.

Simple and super light-weight tracking of profession links for all your alts.

Automate Your GDKP Auctions, Bids, & Payouts

A replacement tradeskill window

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

Helps you automate selling stuff

This will keep track of how much you have paid per item in your inventory. Only one of (Auctionator, Auctioneer, AuctionLite,...

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

LDB data source for currency flow

LDB display of currencies, gold totals and session / daily / weekly statistics for all characters on a server.

Helps you automate selling stuff.

Save and send chat messages to many channels. Allows quick item and profession linking within your messages.

LilSparky's Workshop mod for Trade Skills

Replacement for default bags.

GemCensus inspects people and records which gems they have socketed. Then displays which gems are the most popular.

Helps to find other player's alts.

Simplifies GDKP bidding processes

Collects, analyzes and presents information about the virtual economy.