Both from Sitepoint, one of my favourite resources (ignoring the evil pop-ups trying to get you to buy their books).
The better of the two is on Search Engine Optimization and contains a couple of very good ideas that I hadn’t thought of … and I claim to be good at this kind of thing!
The second deals with testing websites and provides a good framework for ensuring your site is compliant with the relevant standards.
Thanks for the links.
For those evil pop-ups, try clicking on the “don’t show me this again” link which will set a pernament cookie in your web browser.