http://digbig.com/4nqhf
"The 2006 edition of the popular Research-Based Web Design & Usability Guidelines, based on the latest research, has been published. The Guidelines have become a primary resource for government and other web communicators. Since their introduction in 2003, the book has been widely used by government agencies and the private sector, implemented in academic curriculum, and translated into several foreign languages."
Research-Based Web Design & Usability Guidelines
http://www.usability.gov/pdfs/guidelines.html
PDF - http://usability.gov/pdfs/guidelines_book.pdf