Real hamsters make a lot of work and normally don't really fit into the life of a geek. A much better idea is this USB Hamster. As soon as you connect him to your computer (through USB of course) and start typing, he will start to run in its wheel according to your typing speed.
The hamster wheel has a diameter of 13cm and it needs a AA batteries, which is included. The included software only works with windows.
This product is not available anymore.