Worked Full time (or more) every summer since I was 16.
Full time immediately after college graduation, but that only lasted ~13 months (3 working days left?!) due to me entering grad school in the fall.
I'm approaching grad school more like a job than school. I'll get paid, I'll be working summers doing research, etc.
My job only lasting for about a year was planned going in, and my manager was aware of this the entire time.
Timeline:
16 - office lackey at local engineering firm (thought I'd get good experience .. wound up filing. Good people, though).
17 - Machine shop assembling infrared heaters/dryers. Moved up over the course of the summer until I would take order sheets from the sales people, decide which things to build when, manage component production of other employees in order to meet the orders, and package and ship the resulting units. I think one of the managers almost shit himself when he realized I was leaving to go back to highschool in a couple weeks. Spent those weeks doing my stuff and trying to train a series of losers from a local temp agency.
18 - Circuit City, warehouse associate.
19 - Engineering intern with small consulting firm (HVAC stuff for hospitals), and part time at CC for the cash monies.
20 - Intern at the Shell refinery in Deer Park TX
21 - Member of Team Berlin, the Freie Universitat of Berlin's entry into the 2007 DARPA Urban Challenge. This was a ton of fun, insane amount of hours, and basically zero pay.
22-23 (post graduation) - Full time product development engineer working mostly on research/proof of concept type projects for an oilfield services company.
<--- this is the divide between the past and my future plans --->
23-27 (god I hope I get out in four years) - working on a Ph.D. at Cornell
27(or 28) - future - who knows? Maybe industry, maybe academia. I'm fairly confidant that I'll be able to get a position that I'll be happy with, though.