I worked the first 2 years of med school for my school's office of community service and got some valuable experience out of it. It was work I would have wanted to do anyway, and it was actually one of the things that encouraged me to take a gap year to earn my MPH. I worked ~10 hrs/week and I still did well in all my classes, had time to go to the gym, see my friends and family, ect. A lot of my classmates had much easier library or computer lab jobs where you just sit and study 90% of the time and get paid for it. If you can find one that isn't a hassle or requiring too many hours it can be a good thing for a little extra money. But I wouldn't do it just for something to put on a resume.