I heard of MetaFilter through, ironically, fictitious blogger Plain Layne. Her/he and I had been corresponding via chat and our blogs and became somewhat close. Even though he/she didn't have an account I ended up getting one for him/her. We all know where that lead.
We Can/Did Has Monkeys
Somewhere buried deep in the ether of MetaFilter I have a dormant account that I signed up with a year before I joined for real. I think I wanted to put someone in their place so I signed up, said my piece and left. Flash forward a year to the above and I ended up back here. The tipping point for me was the 9622 monkey thread. The irreverence and sheer fun of that thread was enough to keep me hanging on ever since.