A friend sent me a link to a Flash game called Fantastic Contraption. It is quite possibly my favorite Flash game I have ever played. The purpose of the game is to get a ball into the goal area. You can use wheels and rods to build machines to achieve the goal.

There are some great machines that players have created. Here are a few that I have stumbled upon to pique your interest:

Nice Thing
No Power Pult
Chain Swing
Minimalism