WC3 HTML Test - HTML, XHTML, SMIL, MathML, etc
http://jigsaw.w3.org/css-validator/
http://validator.w3.org/check?verbose=1&uri=http://minisites.dev12.visionteam.dk/
MobileOK content:
http://validator.w3.org/mobile/
Links
http://validator.w3.org/checklink
Validators / tools
Browser stat