When I was 15 or 16 (can't remember exactly), I ended up doing contract work for an "Internet Marketing Firm" (read: spammer). I built a ridiculously scalable email crawler and learned a whole lot in the process. I wouldn't do it again -- I would rather not make money than assist spammers -- but at the time it seemed like a good decision. Hindsight is 20/20 and all that.
Same here, I was 17, learning web dev at a small company and the founder had me creating spam-blogs (splogs) back in 2004 when it was effective for gaming SEO. I know better now as an adult.
