I had the pleasure of being in the jury for Global Game Jam 2010 in Turkey. The goal of Global Game Jam is to create a playable game in 48 hours. So, the teams do not sleep and try to create the best game in that very limited time. There were very talented and valuable people in this competition and most of the games they created were very good when you think they only have 2 days.
You can visit Global Game Jam site or GGJ Turkey site for more information.