What it does:
Plays a cash register bell sound every time one of your auctions sells, letting you know that youSold.
Usage example: be alerted of sales while alt-tabbed browsing the web, so that you can replenish stock. Be sure to enable 'Sound in Background' in the WoW sound options.
Notes
About 4.0: Edit: All good, Blizzard fixed the missing chat messages.

