Tools and addons

For years I used Auctioneer. Without the effort that Nechckn and team have put into that addon, I doubt that there would be a community of gold makers in WOW. Over the last few years I have used several different addons. At the moment I use one addon suite to queue of my tradeskill craftables and posting my auctions. Tradeskillmaster. It also supports tracking of your inventory, but I find that it needs to be running on all of your crafting characters to keep from getting confused. So I use another addon, Altaholic for that task.
A quick comment on addons. Unless you have a top of the line system you will see some impact when running any of the larger auction house addons. On my main system I don't see any system lag when it is running in the background, but on my secondary system which has a single core processor and 4gb ram it is noticeable when crafting and sometimes when posting items. This is mostly due to database writes to the hard drive. To combat this I use an addon called Addon control panel to turn off my crafting and auction house addons before questing or queuing for dungeons/raids.
Where do you get these addons? My suggestion for tradeskillmaster is to download it from Curse. for Altoholic and addon control panel you can get either at both Curse and WOWInterface.

Tradeskillmaster:
http://www.curse.com/search?search=tradeskillmaster

Addon Control Panel:
http://www.curse.com/addons/wow/acp

Altoholic:
http://www.curse.com/addons/wow/altoholic