I have written some software. Here's a couple.

Shakki is a standard chess game where you can play against your friend or a computer opponent. You can change the difficulty level and save/load your progress. Only available in Finnish at this time.

Nukku is a Windows Vista/7 gadget which shows you the time you have left to sleep when staying up late at the computer. You can adjust the wake up times for each day of the week. It turns orange when there is under nine hours remaining and red when under eight hours remain.