|A former member||
This is an awesome writing challenge put together by Jeff Goins. He doesn't just have you write, he makes you go out and build on your material (e-mailing, sending things out etc.) You can find it here:
15 Day Writing Challenge
I've been writing about it on my personal blog here: TigerLily's Pad
If you decide to do the challenge, I'd love to read your stuff!!