It's NaNoWriMo again in November - National Novel Writing Month.
The aim is for all participants to write a novel during November. The goal is 50,000 words or about 175 pages. If you register with the official site, you'll get encouraging emails and local offers of meets in cafes where you can bring a laptop and try to catch up while everyone is doing the same around you. At the end of the month, upload your novel, and a robot will count it for you, and if you've reached the magic number, you're a winner. The novel belongs to you, of course. It isn't uploaded for everyone to read and rip off - the robot reads it and that's that. (You can even ROT13 something before you upload it if you're paranoid. Get ROT13 here.)
Last year I wrote 40000 words and then something happened. Vodka, need for sleep, work stopped accepting the excuses that the dog ate my homework, that kind of thing. I think I will register again this year.
If you're one of the approximately 90% of people who think you have a novel in you, go ahead and sign up. What do you have to lose? If you haven't got that far with your novel planning, the NaNoWriMo's founder offers a book called No Plot? No Problem! which will get you over the completely minor hump of not having a plot or setting or characters yet.