I had 3 different part time jobs when I was in college:
1. Security. Basically sit around in a office for late night hours and do walks around the building once an hour. -- got this my freshman year. They were eager to hire anyone willing to stay up until whatever time it was (4am? something like that) a couple times a week.
2. Lab computer admin. Got for the same reason..I worked graveyard the first year or so, then my hours improved substantially thereafter as the worker pool rotates every year.
3. Website designer/programmer. I got this as a fluke from a discussion with a local public organization that I had ties with. They were looking to establish a web presence, and knew I was a "computer guy" so they consulted me to do all the work.
I also took random consulting jobs through a friend who owned a computer services business, and occasionally needed someone with more advanced programming skills.
And I taught English while I was in Japan (and did other related work), but that doesn't really count.