here comes a new CSS layout.
The techniques aren't really new, but maybe the combination of them ;)
My motivation was to create a robust flexible layout for portal software like Plone.
Check it out:
http://www.webproducer.at/flexible-layout/
http://www.webproducer.at/flexible-layout/layout.css
Some highlights:

Min-max width for IE
Everything in EM (change your browser font size to see the effect)
Source ordered
Full height columns
Switch between one two or three columns
Fixed width side-columns