Way more useful:
http://www.bikeforums.net/showthread.php?t=274916

Seriously though, the cheapest and most simple thing to do in your situation is to find an old road bike and follow the instructions on sheldonbrown.com to convert it to single speed. Once you have some extra cash you can get a fixed rear wheel or wheelset and do the fixed gear thing. Look for a bike with horizontal dropouts in your size and have fun.