I am interested in writing tests. I am a big believer in automated testing. I designed and built the free online multiplayer strategy game code.google.com/p/stratinit/ (I got fed up with Sourceforge being so slow and breaking the site when they upgraded it last summer.) I worked hard to build comprehensive unit test coverage for that game. Every time a bug was reported, I would first write a failing test that reproduced the bug, and then fixed the code until the test would pass, ensuring first that the hundreds of other unit tests also still passed. After a while, you have such strong test coverage that you can make major changes to the inner workings of your code with boldness and courage, knowing that your tests will tell you whether your changes break anything.
Ken