National Novel Writing Month. Write a 50k words novel during November.
I don't think you have to be American to participate, I am guessing that the "National" part is just a leftover from the olden days when nations mattered.
If I am to do it, I think an interesting strategy might be just to deliberatly write crap, anything at all. It'll blast through all the internal-editor blockages, and I suspect a lot of ideas and qualities will seep in anyway.
L. Ron Hubbard, who was a high-volume pulp fiction writer, told a story about a lecture he had give at a university, where he said that "when you've written about 200,000 words, you'll know if you have a style". He felt he was being very conservative about that, but it seems he terrified these academia students, because they each tended to write something 5,000 words a month!