www.w3.org/XML/ -- W3C's official XML site; links to specifications, resources, software, etc.
www.xml.com/axml/axml.html -- The Annotated XML Specification, by Tim Bray; excellent resource
metalab.unc.edu/pub/sun-info/standards/xml/why/xmlapps.html -- "XML, Java, and the Future of the Web," seminal essay by Jon Bosak, "Father of XML"
www.oasis-open.org/cover/ -- all the links you could ever hope for
www.megginson.com/SAX/index.html -- SAX 1.0: The Simple API for XML
www.XML.com -- news, opinions, tutorials, etc.
www.xml-zone.com -- magazine, developer’s resources, links, etc.
www.xmlhack.com -- news from the message boards, eg. XML-DEV
www.egroups.com/group/xml-dev/ -- XML-DEV mailing list archives; all the famous guys hang out here
www.refsnesdata.no -- excellent tutorials on XML, HTML, WML, etc.
www.brics.dk/~amoeller/XML/ -- large slide collection introducing XML and related technologies
www.builder.com/Authoring/XmlSpot/?tag=st.bl.7267.plbl -- CNET’s "Spotlight on XML"
www.zdnet.com/devhead/filters/0,9429,2133216,00.html -- ZDNet’s XML site
java.sun.com/xml/ -- Sun’s XML/Java projects
msdn.microsoft.com/xml/default.asp -- Mister Softie on the bandwagon
www.ibm.com/developer/xml/ -- Big Blue’s got some cool tools
www.seattlexml.org -- Seattle XML SIG; meets at Microsoft campus
www.seajug.org/html/mail.html#xml -- SeaJUG Java-XML SIG; does not meet at Microsoft
www.biztalk.org -- BizTalk framework for e-commerce; backed by Microsoft
www.cxml.org/home/ -- Commerce XML
http://www.xml.com/pub/2000/08/02/ebiz/extensible.html?wwwrrr_20000802.ptxt -- a survey of current industry-specific frameworks and schemas (updated August 2nd, 2000)