Simple DC motor

It's interesting that you can have fun with a magnet, paperclips, wire, and a battery. You can see some movement in the first photo. The current flows through the wire loop in the middle creating an electromagnet with north/south poles. These poles interact with the stationary magnet below it and causes the loop to spin. The second photo is one that my brother built after a visit to Radioshack. He did most of the work on the first as well, but there was a lot of changing voltages/spacing/etc..

You can build your own here following some instructions here.
http://www.simplemotor.com/bmotor.htm