I was active in the Los Angeles area in web design and development. I think the first thing I knew of Mathowie was when he would post to the Web405 listserv. He was a smart guy, and an interesting guy, and I enjoyed what he had to say. He also worked at UCLA as a web guy, which is a place I interviewed once to work at but didn't get in.
I'm pretty sure I signed up for MetaFilter when Matt announced his new project on his website, or on the Web405 list, or both.
I have been off and on the site since the beginning. Taking huge chunks of years of inactivity. I'm lately an avid reader and answerer on AskMe.
Matt and I went to lunch
My first best memory of MetaFilter is actually getting to spend time with its founder, Matt.
I had recently moved to San Diego. I kept up with tech events in Los Angeles. Philip Greenspun was an author and web guy who really transformed how I thought about websites. He wrote two books: Database Backed Web Sites: The Thinking Person's Guide to Web Publishing. He was going to speak at CalTech. I drove up to L.A. to see him. Mathowie also went to this. We connected at the event and got a chance to talk. Matt was thoughtful, insightful, and was just starting Metafilter at the time.
My memory is a little hazy, but in my memory we compared notes on building communities (I had just recently founded WebSanDiego), how to handle moderation, and about how to maintain good privacy when everything goes online. He also had a pretty nice digital camera, which at the time was still fairly novel.
Matt struck me as a) much smarter than me and b) as a person with the guts to dive in and program even if he wasn't sure. I was impressed with his ethos about Metafilter -- that it should be a place to share cool stuff. This impulse wasn't about how to charge people, or get funding, just about doing that thing. This was a contrasts with the startups I had worked with at the time, which was, we will do this thing and take a slice of every widget and we'll be rich!
In most way's I see MetaFilter as embodying Matt, and this idea he had -- selfless sharing of cool stuff.