Ok, this one is not a puzzle (unless you're a physics student trying to figure out how it works), but it is a pretty cool toy. Spin the top, and it starts to wobble, then spin sideways, and finally it jumps up on its stem and spins upside down until it stops. Check out the video to see the Tippe Top in action.
Tippe Top has been successfully tested in the "Strong & Flexible" materials.
Have fun!