[kashi]

You could put up signs around campus and around town for any service that you think you could do:

Dog Walking (if you don't mind dogs)
House/Pet Sitting for people going on vacation or out of town for the weekend
Tutoring (as everyone else has recommended)
Typing papers for students who don't type all that well
Computer lessons for seniors (simple things, like Word or Internet Basics)

etc etc etc. Just think about simple things you could do that wouldn't require lots of driving around and not much time, and get paid for. You'd be surprised how many older people want to learn how to email thier grandkids or feel more confident about their computer skills, but are too shy to take a class.