Web Design
d.umn.edu
A huge resource of links relating to web design, including CSS, Accessibility, Flash, Information Architecture, PHP, Usability and many more.
w3.org (DOM Reference)
Here you can find links to W3C DOM Level 1, 2 and 3 recommendations.
mozilla.org (DOM Reference)
This is a link to the most up-to-date reference for the DOM as interpreted by Mozilla and Netscape browser's.
dynapi.sourceforge.net
The DynAPI is a cross-browser javascript library used to create Dynamic HTML components.
devedge.netscape.com
Client Object Cross References - These Client Object References provide information on the common objects used in DHTML for Gecko 0.9.4 (Netscape 6.2.x and CompuServe 7), Gecko 1.0.1 (Netscape 7), Internet Explorer 6.0 as well as the W3C DOM standards.
brainjar.com
Description: An excellent site for DHTML reference, contains detailed explaination of DOM and Javascript.
webfx.eae.net
What you never thought possible! - Great DHTML reference site with re-useable DHTML widgets, this site even has a menu system that displays over the dreaded select form elements.