Looking for Good XHTML and CSS Validation and Development Pages

I’m getting the feeling that I don’t have as many XML Dev peeps as I used to reading my blog — because I didn’t get any suggestions from my last post.
I did locate the W3C XHTML Validator page, and I’m brushing up on the Web Accessibility Initiative tools, as I want my apps to be accessible to all.
I remember there were some really cool CSS tools popping up a while back, so perhaps you could point me to those.
Anyway, I am putting out another call to please send me your favorite tools. I’m a gonna need ’em. — lisa@lisarein.com is my email.
Thanks!