Algodoo

Ok i discovered this by accident. I was trying to make a real speedometer (wich use magnets) so one of my experiments suddenly started to spin out of control. So i replicated it to see if it was by accident... well, it wasn't, it can be recreated as many times as you want.

The light blue one is the original model, runs up to 170 Rad/s
The green one runs up to 273 rad/s more or less. (i actually don't know what exactly determines motors speed)

They are not ultra power full but will move light cars or mechanisms...

How to build it:
-Try doing it yourself... Or
-Check forum post (i'll try to explain it more)

Link to forum post -> http://www.phunland.com/forum/viewtopic.php?pid=81654#p81654