Documentation on Technologies behind XWeb

W3C

The W3C site. They link a lot of useful information and often their recommendations (sometimes hidden as "Technical Reports" in the top right corner) are nice to read and contain lots of examples.

ZVON.org

This site has a lot of tutorials around web techniques, they are available in different formats online and as HTML for download. Very useful stuff.

W3Schools

Another site with a number of good tutorials and very useful references around (X)HTML, CSS, XML technologies and different scripting languages.

iX XSLT Tutorial

This is the first of three parts of a tutorial to XSLT from a German computer magazine (English translation -- not well translated but good enough to understand). The other two parts are linked from this page.

SVG Recommendation, Filter Effects

This is part of the W3C site but since it is really useful for creating fancy buttons with SVG we include this direct pointer. Note that this is quite a big document.

SelfHTML

Very good German reference/manual for HTML/JavaScript/CSS.