Since we're all reminiscing about high-school geek antics: In my Physics class, we had semester long ongoing assignments that were markedly harder than the nightly homework. You could turn in the problems at your own leisure. They were mostly applied problems that involved some math we hadn't learned yet (like calculus). The problems were the same for each student, but we all had different parameters, so our answers would be different.

After figuring them all out a few weeks into the semester, I started writing up some BASIC programs on my TI-86 that would take in student's parameters and spit out solutions. Long story short, I ended up selling answers to some jocks and got caught (I guess the teacher was suspicious when C students were getting these hard problems correct). End result was: made my teacher simultaneously proud/disappointed, earned a few bucks, learned about corruption/greed.

All in all, it was a good learning experience and I don't regret it (though giving away answers for free would have been more altruistic I guess)