When I started dating my ex-husband, he was constantly spending time on this crazy blue website. A few months later, sign-ups opened up. We were living in Iceland at the time and he didn't have a valid credit card that was accepted by PayPal... but I did. So, he begged and pleaded to use it to sign up. I agreed and decided that I would also sign up, because why not?
Seven years later and my relationship with MetaFilter has lasted more than twice as long as our marriage.
I've come and gone, but MetaFilter... I just can't quit you.
9622 v. 2 (aka THIS MESS) was by far the highlight of my MeFi experience. That thread crashed my computer more times than I can count and the silliness helped cut the tension of an international move. I consider being one of the initiators of an in-joke that has since totally taken on a life of its own (the "longboat" which in no way initially referred to a long thread) one of my finest accomplishments.