Site of the Week is a no-brainer: National Novel Writing Month, the marathon-type sprint (try it, and you'll know what I mean) to complete an entire novel in just thirty days, starts in just 11 short days. The website linked has (free) writing guides for middle and high school, and I think adults can use them to (no one will know if you don't tell them!).
I actually made up my own month a couple years ago in April (National Non-Fiction Writing Month) and completed a non-fiction book (along with a student who wrote a book of essays) that I still have not refined and published.
Oh, well. NaNoWriMo is all about quantity, not quality, although famous books have come out of it.
Sharpen your pencils, have a seat, and get writing!