I participated in Nordic Game Jam 2008 from in the weekend 2.-3. of February, which is about making a game in 48 hours. Once you subtract time for sleep, eating and general setup, however, you are only left with about 20 hours to actually get work done.
I wasn’t actually didn’t intend to participate, but went there to greet the other people of the danish games industry i know. Once i got there, however, i got caught up in the excitement and got in a group with a good friend from Zero Point Soft, a few of his colleagues and 4 other talented people.
In the end we had managed to make a mouse driven arcade game which is about trying to keep nuns and muslim women apart before they get into a fight.
We were awarded the audience award by popular vote among all the people participating in the event, so that made us quite happy :)
My good friend Jon Lauridsen has made a nice summary of the process on his blog site.