SEO & Web Site Design Resources
Google Web Conversion University - A wealth of information ranging from how to write effective headlines to help analyzing your web statistics.
World Wide Web Consortium (W3) - the definitive industry resource responsible for developing web standards such as HTML and CSS rules. (If only the browsers would catch up!). There are free tools on this site for web developers to test page coding before launch to ensure compatibility compliance.
Google Webmaster Guidelines - Get your SEO facts straight from the source. If there is an SEO rule book out there, this would be it.
Google 101: How Google crawls, indexes and serves the web. - More Google information.
Google Webmaster Center - Google webmaster tools for those who want to dive a little deeper into the mechanics of SEO.
SourceForge.net - A great resource for open-source software. You'll find auto generating XML site maps, statistical tools and much more.
Black Hat SEO tricks - If you are wondering if your SEO Consultant is using unethical techniques that risk getting your web site penalized by the Search Engines, check out this reference.