Here's a very simple, but tricky little game which could keep you amused for hours, if not days. Basically, you are a dog swinging a cat, which you have to let go at just the right time to launch the cat into orbit. You are helped by the use of a booster pack, triggered by the LMB, which can propel the cat even further away from the earth. Too much too soon and you haven't got enough orbital velocity, too little too late and you crash to the ground... it's very addictive and has quite a surreal soundtrack. The best I've done so far is about 2¼ orbits before the cat comes crashing down, bouncing and meowing to terra firma.
Give it a go if you've got a few 'days' to kill, but beware... you will be addicted.
You need java installed to play.