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

reference sites with tutorials:
Build your first web site
http://www.builder.com/Authoring/Newbies/
by
CNET's builder.com
http://www.builder.com

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

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

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

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

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

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

bonus!
Webopedia - definitions of web jargon
http://webopedia.internet.com/

There are many products on the market that help you to build HTML documents. There are WYSIWIG (What You See Is What You Get) programs, and there are HTML editors, and some people still code entirely by hand.

WYSIWIGS operate like word processing software. You work with the document on your screen, and the program generates the HTML code, which is hidden from view.

With HTML editors, you are working directly with the code, with lots of bells and whistles to support you.

For those of you that aren't familiar with HTML code, it seems like an easy choice to make. However, WYSIWIGS often write superfluous code or code that is meaningful only in one browser. On the other hand, there is a time investment to be made in order to learn code if you're planning on using an HTML editor. At any rate, it is worth the effort to at least become familiar with HTML code. It will provide you with the means to solve problems encountered with web pages, as well as have more control over how your web pages will look.