I've always been a little intrigued by the Segway. I'm fairly sure that even if I could afford one, I wouldn't actually be caught dead riding one, let alone throwing down the cash required for one. If you don't mind being seen on one and have some spare time and money on your hands, you might just be able to make one yourself.
A group of students from several schools including MIT have created their own DIY Segway. Their initial goals were modest: the device must weigh less than 50lbs (including battery), cost less than $1000, have “lean steering” and be able to be ridden through a door.
Needless to say that they managed (almost) all of their goals. They only went over their total weight limit by 2lbs. When stacked up against an actual Segway, their home-brew unit kept up pace quite well with a top speed of 11mph vs 12.5mph in the newer Segways. Despite going over their weight limit they were still more than 30lbs lighter than the real thing. Now that's DIY engineering at its finest.
The DIY Segway [via official site]