I found this great bit of coding http://c4fdevkit.codeplex.com/ while looking for some free software from this article. It shows you how to use the Visual Studio Express Editions to create software you would actually want to use. For example Bluetooth and YouTube, so make a program that finds a video on youtube and uploads it to your phone via bluetooth. The limitations are only the limits of your imagination.
We have talked a lot about algorithms over the last term. This site breaks down the processes that the ghosts use to hunt pac-man.
If you want to practice your games design skills there are a lot of great sites and applications out there.
Here is a list of some software to get you started