www.xml.com
"Oreilly's"

www.xml.org
Hosted on this site is the XML Catalog, which lists organizations known to be producing industry-specific or cross-industry XML Specifications..

www.xmlhack.com
This site is "developer news from the XML community" and focused on actually implementing XML ("XML Resource Guide" e-doc magazine, Nov/Dec 2002, p 19)

www.xmlmag.com
The XML FAQ is the list of Frequently-Asked Questions about the Extensible Markup Language. It is restricted to questions about XML It is intended as a first resource for users, developers, and the interested reader, and does not form part of the XML Specification.

XML Web Sites - Standards Organizations

www.w3c.org/XML
The World Wide Web Consortium (W3C) develops interoperable technologies specifications, guidelines, software, and tools) to lead the Web to its full potential as a forum for information, commerce, communication, and collective understanding.

www.oasis-open.org
OASIS, the Organization for the Advancement of Structured Information Standards, is a non-profit, international consortium that creates interoperable industry specifications based on public standards such as XML and SGML.

www.ebxml.org
ebXML is a set of specifications that together enable a modular electronic business framework. ebXML enables a global electronic marketplace where enterprises of any size and in any geographical location can meet and conduct business with each other through the exchange of XML based messages.ebXML is a joint initiative of the United Nations (UN/CEFACT) and OASIS, developed with global participation for global usage.

www.opentravel.org
The Open Travel Alliance has successfully recruited well over 150 travel industry organizations, including airlines, rental car companies, hotels, cruise lines, etc, in support of its critical ground-breaking work of developing communications standards (in XML) to allow for the efficient and effective exchange of travel industry information via the Internet.