My first entry (authored together with “Mtv Europe”) was a chess playing program. You can look at the remarks, and you can download the program. I am particularly pleased with this entry - the formatting is really cool, and it plays chess absolutely hopelessly.
My second entry was a utility to hide files steganographically in other files. You can look at the remarks, and you can download the program. It was quite neat to hide the steganographic encoder program inside the decoder program - which is the program provided. You just need to run program on its own source, and you get the encoder program.