www.seobook.com/robots-txt-vs-rel-nofollow-vs-meta-robots-no...

This is a table of the three type of Nofollow compared against each other

stackoverflow.com/questions/14196801/sitemap-url-in-robots-t...

This thread tells you how to references your sitemap in the robots.txt

tools.seobook.com/robots-txt/

Generate effective robots.txt files that help ensure Google and other search engines are crawling and indexing your site properly.

www.askapache.com/seo/seo-with-robotstxt.html

Very nice tutorial dealing with the robots.txt file. Shows examples for google and other search engines. Wordpress robots.txt and phpBB robots.txt sample files.

humanstxt.org

An initiative to know the creators of the website. Contains the information about humans to the web building.