Envizio Wheel Wizard
Beng posted this link over at Odyclub and I thought it was amusing. It's a wheel selector that allows you to customize your vehicle by choosing size and type of wheels as well as colour and suspension height. Then you select a background (unfortunately there are only 3 available) and you can pan, tilt, and rotate until you get the look you want. Once you are done, you can render the image and email it to anyone. It's pretty nifty, although the rendering of the STI came out kind of dark. I also wish there were a better selection of wheels available.
Note: You do have to install a plug-in to get it to work, but it's small and fast and works fine in Firefox (I don't use IE).