Appearing at the 2009 Bay Area Maker Faire is the Mendocino Solar Motor:
The motor is pretty easy to get right. The construction difficulty is not easy or medium — definitely “hard.” It is best if you have good soldering skills, and the ability to think about the theory of the motor so that you get the polarity of the cells correct. Make sure the current flowing through the bottom of the coil flows from left-to-right every time that part of each coil is closest to the base magnet.
The Mendocino Motor is a great project for teaching kids about solar, electricity, soldering and more. The Mendocino Solar Motor should be a great maker exhibit to check out. You may want to look at the complete list of the Bay Area Maker Faire 2009 exhibitors.