Here are a few examples. One will feed you greasy bacon every morning. The other will donate to the GOP. Others will force you to perform either menial or mental tasks. I prefer a more gradual approach – a system that gradually increases the illumination in the room, the volume of sound (some pre-chosen music), etc. and only does something dramatic at the last, most critical point in time when you absolutely HAVE to get up.
[btw, check out the other pages on that site – there are some other cool inventions there, mixed up with some quite silly ones]