Yeah, I did this past 24 hour contest (an International collaboration with fellow board member Monglane in Paris). That was my fourth one. They screen on Friday/Saturday.
I did the 48 hour last year and highly recommend it... 24 hours is very short, but 48 hours is enough time to come up with something decent. I can't do it this year though, as I'll be out of town.
I pitched for Crazy8s this year, but didn't get it.
The next one is the 72 hour in Whistler this weekend, which I'm just helping out on (and donating my camera to), and then the Straight8, which is a Super8 event.