I had the great opportunity to attend and speak at StartUp DC's Ideas Summit which took place January 31, 2012. They held a crowd-sourced competition for ideas to be included in the event and I was fortunate enough to get first place among dozens of fantastic ideas.
The event was held at the fabulous Geekeasy, the DC's tech startup co-working community.
Below is my talk about finding high-quality, and preferably, centralized meetup spaces. The kind folks at meetup.com provided some preliminary charts on meetup statistics. They recently released official data at the New York Tech Meetup. The full video of the idea summit can be found here.
Lastly, WashPo has a nice summary of the event here.