This is the best all-around Faulkner site I have yet encountered. You've got bios, book summaries, and even (prepare yourself!) Faulkner games:

http://www.mcsr.olemiss.edu/~egjbp/faulkner/faulkner.html

These are good sites for biographies:

http://www.olemiss.edu/depts/english/ms-writers/dir/faulkner_william/

http://www.littlebluelight.com/lblphp/links.php?name=Faulkner

This is a site with a lot of sound Faulknerian criticism:

http://www2.semo.edu/cfs/teach.html

Faulkner's Nobel Prize acceptance speech: great insight into the man!

http://www.nobel.se/literature/laureates/1949/

Here are a couple of the official Faulkner websites, The Center for Faulkner studies and The William Faulkner Foundation:

http://www6.semo.edu/cfs/

http://www.uhb.fr/faulkner/WF/index.htm

Here is a hypertext edition of The Sound and the Fury, my personal Faulkner favorite, along with all sorts of helpful critical parphanalia:

http://www.usask.ca/english/faulkner/