The SeeSS widget for the OS X dashboard “is a quick and handy reference sheet for 140 CSS (1, 2 & 3) properties (proprietary extensions are not included). Each property includes information on its inheritance, CSS compliancy, Safari support, all values (including defaults), some examples and an extensive description. A link to the appropriate W3.org pages is included as well, for even more additional information.” This looks quite handy for those running 10.4+. Link found via Veerle’s blog