As Gregory Narain, at syncpeople, works to launch the application that I think will revolutionize interaction at conferences and turn conferences into online communities, Dana VanDen Heuvel blogs about the tools that people are using (without conference organizer's facilitation) to make conference social interactions start and end before and after the event:

1. A blog (of course)
2. A wiki
3. A Frappr map (like Loic's) of conference attendees, speakers and followers
4. A del.icio.us account tracking links about the conference
5. A flickr photstream with conference photos, tagged with the appropriate keywords
6. A technorati link to the conference keywords & tags
7. Buzznet Buzzwords

This is an area that I am especially interested-in, as President of WhizSpark, an event management platform for all kinds of events.