A scheduling system for the school.
I worked part time at my school, and knew many of the admissions officers. While my team and I were trying to figure out what to do for our project, I showed a little program that I created to the head admissions officer and she loved it.
I hated trying to schedule my classes. I would color boxes onto transparencies and lay them on each other to find schedules. I whipped up a little program with Java and Swing that would read in the times courses were offered and would show me every permutation of the schedule, giving me at least X hours. This meant that instead of spending a couple of hours trying to figure out a schedule (and change it as classes filled up), I could type in a couple dozen lines from the course catalog into a simple CSV like format and have my program display possible schedules for me.
It looked quite nice, which was probably a help. Basically copying the way iCal shows things helped there.
So for our project, my team and I took my little program and added a database back end and web front end that would allow the administrators to easily add/update classes so that students could always get the latest update of courses without having to filter them by hand with open/closed courses. We also added additional features such as supporting more schedules (half-semester classes instead of just full, etc.), printing (which was a big challenge), and more.
It was actually a pretty fun project. I'd love to know if they use it, but I haven't asked. The corporate office was apparently interested in it. I found my program very useful, I really hated trying to piece schedules together.
It had it's problems. The PHP front end to the database was rather ugly, but I knew that at the time. Having it connect directly to the database was a mistake. It couldn't do much thanks to right limits, but it should have asked through a web-service or something easier to secure/replace.
Still, I learned a ton, especially with the requirements that I never would have thought of based on real world scenarios that the school had to deal with. It had to be able to show more than 8 different courses on a schedule and handle over 50 hours a week, both of which one poor student took once.