W3C - Cascading Style Sheets - Authoritative information from the W3C. Provides complete specifications, lists of CSS browsers and authoring tools, and information about learning CSS.

Cascading Style Sheets: Celebrating 10 Years with Style - W3C mini-site to mark the 10-year anniversary of the first published CSS recommendation. Includes time-line, hall of fame, essays, and a gallery.

Code Style - CSS Style Guide - Includes a cross-platform font sampler, information on media stylesheets, FAQ, and a glossary.

CSS Naked Day - On April 5th, simply remove all CSS from your website, stripping it entirely of its design. Promoting web standards, plain and simple.

css-discuss Mailing List - Practical discussions of CSS and its use. High volume list.

CSS3.info - Newest developments in CSS based webdesign.

Dive into Mark: CSS - Archive of postings to Mark Pilgrim's weblog.

Eric Meyer - CSS - Articles, tutorials, discussion and resources for CSS.

EServer TC Library: Cascading Style Sheets - A collection of dozens of rated, reviewed online resources for developers who work with cascading style sheets in web and information design.

Web Developer's Virtual Library - Cascading Style Sheets - Teaches how to use CSS to improve the look and structure of HTML pages. Links discuss how to use CSS to avoid table layouts, colors, fonts, and layers.

WebmasterWorld: CSS Forum - Discussions on layout, compatibility and trouble shooting.

W3C CSS Working Group Blog - News, announcements, and opportunities for discussion from the group working on the next CSS specification. [Atom]