I'll add more to the list when I've found more information here.
1. Internet Explorer & CSS issues
2. Ten ways to speed up the download time of your web pages (some key points here, a must read article.)
3. Ten CSS tricks you may not know (There are some tricks here that you shouldn't miss too)
4. CSS Help Pile - A huge pile of CSS-related tips, tricks & resources.
5. 53 CSS-Techniques You Couldn't Live Without (Here, you can learn the specific technique that you want to use in your web site. Another Must Read article.)
6. Layout Gala: a collection of 40 CSS layouts - Here you'll get some reference CSS layout sites.
7. MaxDesign - Sample CSS Page Layouts (with step by step layout tutorial too)
8. CSSplay - There are some demos, menus, layouts, boxes examples.