CSS Links

CSS Validators

CSS Validator http://jigsaw.w3.org/css-validator/
CSS Validator http://www.w3schools.com/web/web_validate.asp

Learning CSS

W3Schools http://www.w3schools.com/
CSS Resources http://www.webdesignerdepot.com/
CSS Articles and Tutorials http://www.w3.org/Style/CSS/learning

HTML and CSS Forums

CSS-Tricks http://css-tricks.com/forums/
Web Design Forums http://www.webdesignforums.net/
Web Design Forum http://www.webdesignforum.com/
Designers Talk http://www.designerstalk.com/forums/

HTML and CSS Editors

NetBeans http://netbeans.org/
Adobe Dreamweaver http://www.adobe.com/products/dreamweaver.html