I know most here aren't a fan of the site, but Reddit does this and the meetups are a blast. They're usually geographic or interest-oriented, but there are some bigger ones that inspire travel. You do get the negative you'd expect, but that's the Web in general. Don't go just to get laid (you won't), treat people with respect and it's great. I suspect there would be different problems with this audience, but all manageable.

They get pretty fun beyond a critical mass but that usually takes logistics, sponsors, and so on, and you're basically organizing a conference. I think Imgur had sponsors for the last big one and fed everybody the whole time. There's a spectrum. Small and intimate can be good, big and organized and logistical can be good. Sets the tone.

Get one or two of the heavyweight names here to talk, toss out some Goat Hill, and you'd draw a crowd.