HTML5 shiv: http://code.google.com/p/html5shiv/
Modernizr: http://www.modernizr.com/
Colors: http://mattpatenaude.com
Compatibilidade de fonts: http://webfonts.info/wiki/index.php?title=@font-face_browser_support
Gerador de fontes: http://www.fontsquirrel.com/fontface/generator
Transitions: http://css3.bradshawenterprises.com/transitions/
Gerador de degradês: http://gradients.glrzad.com/
An Ultimate CSS3 Generator List: http://www.thedesignwork.com/css3-generator/
SASS: http://sass-lang.com/
Compass: http://compass-style.org/