If you need to know what XML tools are available, you couldn't ask for a better site than XMLSOFTWARE (http://www.xmlsoftware.com). This site, currently maintained by James Tauber and Linda van den Brink, is updated on a regular basis.
XMLSoftware also offers e-mail notification when new items are added. The authors maintain other sites devoted to XML implementation and tools, including a schema repository. These other sites include XMLINFO (http://www.xmlinfo.com) and SCHEMA.NET (http://www.schema.net). TheXMLSoftware site contains links to these sites.