HTML
This is w3c's home page for the xhtml2 working group.
http://www.w3.org/markup/
CSS
W3c's overview of web style sheets: css.
http://www.w3.org/style/css/
Java
Get the latest java software and explore how java technology provides a better digital experience.
http://www.java.com/
RSS 1.0
RSS 1.0
http://web.resource.org/rss/1.0/
XML
XML
http://www.w3.org/xml/
XMPP
XMPP
http://www.xmpp.org/