• CSS Crib Sheet, a good place to start, or come back to, when designing sites. A list of basic rules to follow.
• CSS Vault, “A collection of CSS resources and CSS sites that help to inspire and teach every designer.”
• Sleight, by Youngpup, an excellent javascript snippet to take advantage of PNG alpha transparency across browsers (even IE) without adding the messy hacks in your code. His site is a work of art too, very progressive.

Enjoy.