I made a comment on a large and well attended blog to help calm someone down.The blog owner liked that and other comments I had been making to ask me if I would accept the offer to be a moderator.That was two years ago and still a moderator there.
I've been a mod in 2 communities: karateforums.com and phpbbhacks.com. Both are run by Patrick O'Keefe, who's (in my opinion) one of the best forum admins ever. I really enjoyed working with him and it was a great honor to be a 'staffer' there. Have learned LOADS about forum management. So, what attracted me was the chance to help 2 of the communities I really love and get first hand experience from a top admin.
Buttons I can push! In reality, I moderate because I like to help create a community I love to participate in. Might sound too general and far-fetched but that's me.
I am a perfectionist, when I see something goes wrong or not tidy enough, I really feel like helping. But forum admins will not simply trust you to let you be moderators that easily. :/
OCD. Seeing SPAM/posts like "please delete..." always annoy me, simply because of my OCD. Also during the summer I have little to do, so being a part of a community where I can be of use is always good. (And I like all the buttons to push... )