DynamicDrive.com

Awsome resource! A bunch of tips and examples on everything from 2-column designs to menus.

SearchEngineFriendlyLayouts.com

This site focuses on site layouts that search engines finds easy to index. Mainly 2-columns and 3-columns.

CSSDrive.com

This site contains many usefull tips and examples on everything from 2-column designs to menus.