Script Frenzy

The folks at NaNoWriMo have begun a new event called Script Frenzy where instead of going flat out to write a novel in a month, you write a feature-length movie or play. It is free, it is crazy, and registrations are already open. The insanity begins in earnest in June. You have nothing to lose but your belief that you can't do it... and you can have a lot of fun besides. You will be surprised what you are actually capable of.

http://www.scriptfrenzy.org/