A friend (Warren Samu) and I started a project to try to leverage the popularity of World of WarCraft and Craigslist. We figured players would like an outside source to set up trades and look for goods. It was extremely customizable down to the faction and realm a given character was on. But, alas, it did not take off and the in game system proved magnitudes more useful than an outside source could ever be. Anyway, you can see a (mostly) working copy of the site here: http://khadgarslist.thomasle.info
The site is not functional, of course, because this was just to show some of what I have done with PHP. I might get it a little more functional in the near future, but for now it is just showing the layout of what it looked like. At one point (but since I have lost the functional code because of a recent server crash and my backed up files) the user was able to register an account and create different characters for servers so that a search was specifically based on their faction and server. We thought it would be annoying to search for an item just to see it was not on your server.