The 3-Day Novel Contest
Grand Prize: Publication (summer 2008)
2nd Prize: $500 cash
3rd Prize: A great literary prize pack
You have to register for the contest by August 31, 2007 so if you're interested, you'd better hurry up and sign up. And be sure to check out their Survival Guide and the Community Forums... I would imagine that both of them are probably essential if you're to maintain some shred of sanity during this event.
For those of you who decide to do this: Good luck! And may whatever gods of writing you worship be with you during this period of temporary insanity.