Re: adding support for ie6 unsupported css2?
seems to have a pretty complete listing of the css2 capabilities of browsers, and eric meyer's css2 test suite
looks to be pretty full-featured. maybe fixing selector support as well?
off the top of my head, tho, one thing that always bothered me abt ie6 is that its support for elements w/multiple classes was especially borked; acc. to the chart it says the last declared class is the one used by ie6. also, setting display to any of the table values for non-table elements is non-existent as well. i've also yet to run into the off-by-1px error in non-percentage values of widths or heights or position, but almost always run into the double-margins on floated elements (which seems to happen less frequently since incorporating jqueryUI's ui-helper-clearfix class).