Firefox Browser

Information for about:config

Google Chrome

Internet Explorer

Test in IE Browser on Mac or Linux

IE 9 Beta Guide for Developers

Selectivizr CSS3 pseudo-class and attribute selectors for IE 6-8

Turn Off Images

Tools > Internet Options > Advanced (tab) > Multimedia (settings) > uncheck Show pictures

Or use Steve Faulkner's toolbar for IE > Images (menu) > Remove CSS images

And more Web technologies get bastardized (XHTML and SVG implementation)