I did! When I was in high school, I went to the Careers Camp once (1999) and Advanced Careers Camp twice (2000 and 2001) at the SeaWorld in San Antonio. I had an absolute blast! It was a lot of grunt work (scrubbing buckets, prepping fish, etc.) but that all paid off when you got to play with the animals for a bit. If you're thinking of working with animals, I highly reccommend it - it gives you a realistic, hands-on look at the day-to-day activities of animal keepers and trainers.
I actually made a long page for it, detailing everything I did, with pictures and all!