general reference and tutorials:
Yale Web Style Guide
http://info.med.yale.edu/caim/manual/contents.html

Web Monkey - brought to you by Wired
http://www.hotwired.com/webmonkey/

web design:
Lynda Weinman - graphics guru
http://www.lynda.com/

Web Pages That Suck - a reverse look
http://www.webpagesthatsuck.com/

usability/accessibility:
Jakob Nielsen - web usability guru
http://www.useit.com/

Usability 1st
http://ww2.usabilityfirst.com/usability/index.html

checking your HTML:
Bobby
http://www.cast.org/bobby/

Creating Killer Websites
David Fleming, 1997

Designing Web Graphics.3
Lynda Weinman, 1999

The Non-Designer's Design Book
Robin Williams, 1994

The Non-Designer's Web Book
Robin Williams, John Tollett, 1997