(This is an old page. I need to update it…)
Some good HTML5, CSS3 resources:
http://www.html5rocks.com/en/
http://www.modernizr.com/
http://caniuse.com/
http://html5boilerplate.com/
http://code.google.com/p/svgweb/
http://raphaeljs.com/
http://code.google.com/p/canvg/
http://mbostock.github.com/d3/
http://css3generator.com/
http://css-tricks.com/examples/ButtonMaker/
MVC JavaScript Frameworks