I have participated in 3 startup weekends. I never started a company with the projects that I worked on, but I never intended to start a company from a startup weekend project. The reason I go to startup weekends are to have fun and network with other like-minded individuals. The people that I met at the events have helped my business. I have seen some neat companies start from startup weekend like Zapier (called snapier at startup weekend), MedSocket, and Nudge.
Zapier co-founder here, we started it during the weekend and just kept it alive! ;-)
It is helpful to work with people you know and are comfortable with (because if you do keep it alive, you'll basically be married to them). Plus, it helps to have a real business under the hood (not that weekend hacks are bad, but they usually die almost immediately).
I was at a startup weekend that had 'hipmunk' and it seems to be doing well right now...:) wish I'd jumped on their group rather than the one I was on.
