I've been working pretty much constantly since I was 13. My summer jobs in order:
corn de-tasseling (every some town boy does this in Indiana I think)
Christmas tree trimming (13 yrs old wielding a huge machete
Military school dining hall.
Hotel front desk day/night shift
Jobs while in school:
High school - student center/lounge in the high school
College - copy shop, catering (free food
I would say the best part time job I had was my catering job in college. I got a lot of free food, that was actually food (read: not fast food), flexible hours, and I got to pick when I worked by signing up for jobs instead of being told when to work. Plus I didn't have to do any real food preparing or cleaning, just put the plate down and pick it up for the most part. If you have this kind of work where you are, I would recommend it.