The Complete CSS tutorial
Covers many of the important topics.
CSS Tutorial
A good place to start. Covers everything about CSS.
This specification defines
Cascading Style Sheets, level 2 (CSS2). CSS2 is a style sheet language that allows authors and users to attach style (e.g., fonts, spacing, and aural cues) to structured documents (e.g., HTML documents and XML applications). By separating the presentation style of documents from the content of documents, CSS2 simplifies Web authoring and site maintenance.
[HTML and CSS Styling] The Basics - WDTalk.com
This is a guide written by our very own Armatik. It covers the basics of formating text using css.
Max Design - standards based web design, development and training » css
This will help anyone learning CSS