Powerful permanent magnets are fun to play around with and experiment and learn from. Aptly named Instructables user Magnetic Games has a short 2 step instructable that shows how to make a few neat things.
Actually, his YouTube channel is full of interesting experiments and toys you could make with ease with magnets. I think the gears are pretty cool, and of course the accelerators are awesome, very MAC cannon like, which is a type of rail gun.
Unfortunately, none of these things are perpetual, so they won’t solve all the world’s problems at once. But they will get kids thinking of new ways to try things, and with better electricity, and better components, we might be able to come up with innovative ways to do things using magnets. Because Magnets Bitch!