My first actual job was when I was 15-17 (sophomore until senior year in high school, i think), working in the daycare of a gym. If you like kids, I'd definitely recommend this! It was great because there were always at least 2 of us on at a time so you got to hang out with someone, and when it was quiet we'd just watch Disney movies and stuff with the kids. And if kids were acting up, their parents were just a couple yards away on a treadmill or whatever, so we didn't actually have to discipline or anything!
In addition, I worked one summer in the office at my dad's work answering phones, and the summer before going to college I worked at a Pier 1 Imports--I basically spent the day folding napkins and straightening glasses, blaahhhhh.
After I got to college the only jobs I've had since are things "in my field". I didn't do any more service type work, or just-make-a-few-bucks work.
"I don't know! I don't know why I did it, I don't know why I enjoyed it, and I don't know why I'll do it again!" -BART SIMPSON