Nice job. That's new startup #2 today (chompchompdead.com) - which is definitely motivating.
My only criticisms are: Really cut down on that huge red banner at the top. I think most of it is dead space, and one thing that annoys me is having to scroll down on a home page just to see the content. What you can do is move that red banner towards the center and segment it into 'read,' 'write,' 'rate,' to explain the site and have your big 'sign up' button underneath. Also, you might want to jazz up the nav bar seeing everything else seems nicely polished. I think your description of the purpose of the site is a bit confusing and not as direct as it should be, personally. I had a bit of a hard time understanding it. Maybe you should have the login form right on the front page, extra clicks are tedious.
The color palette is pretty soothing and nice to look at. The only thing I might change is to maaaaybe somehow differentiate the ads on the side from the main content of the site.
It'd be cool if you used cafepress or any other service to physically publish the book when it is complete and give those who made it in the book a cut of the book sales, but that's definitely not a primary concern.
Congrats on launch. Sounds cool.