I am not sure I would advise but some people just dont have a choice. That said, the best jobs are 'sitting jobs'. For example, I have a friend that works in the reserve/reference portion of the library. Basically she comes in, picks up a few books at the beginning of her shift, and then studies the entire shift only interrupted by a few questions here and there. At the end of the shift, she picks up books and replaces them etc. It's pretty mindless AND you are FORCED to study otherwise you might die of boredom, and its quiet....all for 7.50-8.00/hr depending on the school.
Other great jobs that people are known to have: ER receptionist/clerk (work at late night) if its a slow ER can basically study also; MCAT prep...very flexible in terms of number of hours and good pay...also teaching the bio section helps a bit with some portions of year 1 curriculum...at least you dont have to RE-STudy the basics; Work-study is great because your employer knows you are a student; Research Assistant/Tech - there do exist jobs where students just clean glassware, maintain animals, order supplies, make reagents...pretty much very brainless lab work as opposed to ACTUAL research; Retail - I would suggest places like a 24 hour Walmart, so you have a pretty wide range of hours to choose from outside of the normal class hours.
I don't plan on working during medical school, but it terrifies me actually because I have never NOT worked. We'll see how my financial aid works out. It is definitely a difficult task....but DOABLE depending on how diligent you are as a student.
To the person that knew a guy that was working fulltime making 100K while in school....what's was the point of that? Just work...you certainly are making enough money...
Goodluck OP!