i have actually been pretty lucky, i haven't been injured too badly, considering the amount of sports i play - gymnastics, field hockey, track, etc...
probably the worst was that pulled muscle in my stomach. it hurt SOO F*CKING bad. you really use your stomach for a lot more than you may think.
after that was probably when i broke my finger last summer. it got caught in my coach's shoelace and got all twisted and it was gross. but it actually hurt a lot less than it looked. i had to leave camp for 2 weeks, though