One of the best sites for clean, clean and yes cutting-edge CSS is Stu Nicholls'
Cutting Edge CSS.
I've integrated many of his examples into my projects including 3
column
layout with DIV's and a nice 3-D tabular effect for
menus
.
I always try to check this site to see if there any updates because
most of Stu's examples make it easier to design standards compliant
pages with nice functionality.