Digital-Photography-School.com has a forum where folks propose assignment ideas, like "Ghetto Lighting" (using everyday lighting like a desk lamp or flashlight), minimalism, eyes, rivers, shadows, self portraits, feet, etc.
At the end of a school year I asked students to type me a little note about what they liked/didn't like about the class. I only had handful of students take the time to do so. One said there were too many projects to complete, and another said she wished I had more assignments because when she finished early she was bored. So, I think I'll make a folder of extra lesson ideas for "If you Finish Early"... or something like that. I'll get some of the ideas from this website.
One of the assignments was "From the Hip". The most exciting one was actually, "Above the Head". I'll think I'll "steal" that idea. It forces students to try different angles and adds some mystery, since you can't see your LCD or viewfinder. Maybe I'll make it one of the steps in an "Overhead Point of View" assignment. Sounds like fun to me.
Also, check out their Digital Photography Tips section with topics like: 10 Ways to Take Stunning Portraits.