A colleague of mine recently mentioned the ThinkQuest site as a place for students to browse and create projects. Early in my teaching career I was asked to help "coach" a ThinkQuest competition team, and the team made it to the finals in Switzerland. There were three students involved, one from Salisbury where I was teaching, one from Taiwan, and one from Estonia. They were were great to work with, and it was a wonderful experience.
If you're interested, you can check out their creation here: The Learning Curve.