Back in my younger days I would participate in Odyssey of the Mind, a competition where teams of kids would do certain activities under limitations. It was quite fun to try to problem solve and think of solutions to problems that at first glance has no obvious answer. Nothing was quite like it, until I found the game Fantastic Contraption.
The goal of the game is to get the pink object into the pink goal area. The tools that are available to use are; two kinds of gears, a wheel, and two types of sticks. From those pieces you have to figure out how to beat each level.
I have to say that this is one of my favorite games on the internet, it might possibly be THE best one. I have beat all 20 levels and I am contemplating coughing up $10 to get more levels. Warning: If you have work to do today I do not suggest you start playing this game.