This online tool can be used to optimize CSS in your webpage.
You can find all CSS properties listed alphabetically here.
You will no doubt come across many quirky layout issues when building a site with CSS. You'll end up banging your head against a wall time and again. This is an attempt to make the design process easier, and provide a quick reference for you to check.
A very good CSS based tutorial site.
Introduction to using CSS to create websites which contains frames without actually using frames.
Pure css tooltips by santaklauss
The Web's CSS Site
How To write Efficient CSS
It contains more than 150 pages with CSS and JavaScript tips and tricks, and is one of the best sources on the WWW for studying and defeating browser incompatibilities.
simple CSS menu designs for you to download and use any way you see fit.