I just did kind of a recap of my startup career over on my blog at http://www.whattofix.com/blog/archives/2007/10/who_me_worry.... Perhaps tonight is the time for people to think about these things.
I read a really great article that was linked from here a couple of weeks ago. I'll use a baseball metaphor to describe it. I hope you'll understand the reference. The point was that it's not hitting the home runs that matter, it's getting the times at bat. That is, if you're always swinging, and you're always learning, it's just a matter of getting enough pitches.
You want to fail fast and learn from it. What I've found that sucks is that to qualify an idea, generate the site, and really get humming might take 4-8 weeks. This means you can't just try out ideas by joining a group for a couple of weeks. Ideas need to be beaten, nurtured, and planned. So if I had any criticism, I'd say "go out there and build something that works, then ask what did you do wrong". Because failing is fine, as long as you keep failing forward.