Shark Pong
Shark Pong was part of the Texas Aggie Game Developers' One Week Game Competition back in 2006.
The idea was pretty simple: you have to make a game in one week, start to finish. I made a simple flash game about sharks.
It is basically pong, but the controls are different - you don't have direct vertical control as in pong. All you can do is tell your shark when to jump. Also, you can move horizontally in the water to "crowd the net" so to speak.
If you time it right, you can eat the ball/fish for a point instead of trying to hit it into your enemy's goal. Also thrown into the mix is a baby seal who ocassionally falls into your side of the water, and is worth 2 points to eat. In the end it was well received and I won a prize. It needs better hit detection, but what do you want, I only spent a week on it!
The best part of the whole experience was the article I wrote about it that got published on Gamasutra.