1. turn it into a dvr or media center pc - actually that is a perfect use since it is so quiet and can run in clamshell mode.
2. give it to a family member for Christmas.
3. web server - it can also host your time machine back ups wirelessly. attach an external hd and get an N card for it.
4. use it around the house - with screen sharing into your imac.
5. have it run folding 24/7