Here are the links to some applets and a little description for each of them.
The most bugless applet I just finished, is the game reversi which can be played with computer or through internet. The game against computer is interesting because computer can learn when he loose.
Just try it.
Universe applet is some simple simulation of particles movement in universe. You have to put any particle type in any 3D location, and press "pause" to start the movement. Many features are in plan to be added, but at the moment there's no time for them.
Here you can find it.