This appears to be the most exhaustive list of
links on the subject of CSS out there. If you need to find a CSS site,
it should be here. Created by the CSS Pointers group (Toby Brown, Jan
Roland Eriksson, and Sue Sims.)
"The House of Style" from Western Civilization Software.
An excellent one-stop resource containing tutorials, references,
comprehensive lists of browser quirks and annotated versions of the
"Why style sheets are harmful" by Jukka Korpela.
An interesting counterpoint essay to the typical endlessly-positive
cheerleading for the use of style sheets. You may not agree with
some or all of his arguments, but they are important factors to
keep in mind.