FAQs, Help and Tutorials
XML Schema 2001 and Relax NG Tutorial, XML Schema Best Practices, XML Schema FAQ, XML Schema Tutorial at W3Schools, XML Schema Tutorial at xfront.com
Standards Documents
Errata in XML Schema, Techquila XML Schema Spec Browser, XML Schema Part 0: Primer, XML Schema Part 1: Structures, XML Schema Part 2: Datatypes, XML Schema Requirements, XML Schema: Formal Description
Tools
CortexML, dtd2xs, LMX: XML Schema to C++ binding compiler, Microsoft .Net Online Schema Validator, Microsoft XSD Inference, OSS Nokalva XSD Tools, Pedro, Schema2Java, SchemaViewer, Stylus Studio XML Schema Tools
W3C Official Public Site for XML Schema
Contains status information, links to specifications and tools that implement XML Schema
W3C XML Schema Test Collection
Collection of test schemas used to ensure consistency among XML Schema implementations.
XML Schema Reference at Zvon
A complete hyperlinked reference for XML Schema which can be downloaded for offline use.