I'm really curious to see just where this project ultimately goes. Will students break the mold and go above and beyond, or keep it simple to meet requirements? Will they make an attempt to make a dent in the universe, or be happy filling out a rubric? Already I've heard some really inspiring real-world assignments, while also hearing some research-paper substitute projects which don't really do more than report content. It's the double-edged sword of teaching seniors: they're at the best they've been at school, yet so close to the end they can't help but slack. This project will define some of them, and slip into oblivion for many others.
For now, it's time to brainstorm. What would you do with 20% of your time free?