[aephi alum]

How about grading problem sets? I did that one semester. For a few classes in my department, the dept. would hire undergrads to grade problem sets and take some of the stress off the TA's. You had to have taken the class the previous semester and earned an A. It was only good for about 8hrs/wk and the pay wasn't great, but you could do the work whenever you wanted as long as you got the problem sets back to the TA's in time for them to record the grades and return them to the students. It was also a good way to keep the subject material fresh in your mind.

Another popular on-campus job was working at your dorm's front desk. Usually this meant sorting the mail, handing out keys to the weight room / music room / study rooms / etc., handing out keys to people who'd locked themselves out of their rooms, buzzing in visitors... nothing too crazy. It works well because they acknowledge that classes take precedence over work, plus if it's not too busy, you can work on a problem set or paper during your shift.

(I know of a guy who did something very clever: There must be a deskworker on duty whenever the dorm is open, for security reasons, and the dorms stay open during holidays. This guy had to write his senior thesis. So he arranged to stay over winter break and offered to work desk throughout. Since hardly anyone was on campus, he had almost nothing to do in terms of deskworker duties. So he took his laptop with him to the front desk, sat around and wrote his thesis, and got paid for it (time and a half for Christmas and New Year's to boot!).)