I participated in 2007, 2009 and 2010. I will give it another go in 2011, but right now I have no idea of which genre to tackle next. Of course the books are poorly written, but that's not the point. The goal is to write fifty thousands words that you can edit later. No editing or proofreading during November...just free form writing.
Good luck to anyone who give this a try. It is a lot of fun. The website is http://www.nanowrimo.org.