Sarissa: Open Source Cross-Browser Wrapper for Native XML APIs

This is very cool:

Sarissa is an ECMAScript library acting as a cross-browser wrapper for native XML APIs offering XML related goodies like XML Document instantiation, XML loading from URLs or strings, XSLT transformations, XPath queries and more.

Supported browsers are Gecko based like Mozilla and Firefox, Internet Explorer and, last but not least, KHTML based browsers like Konqueror and Safari (no XSLT/XPath in these two yet).

Dual licensed under both the GPL and LGPL.