A number of other XML standards exist that I don't go into here. In addition to widely-applicable standards like Scalable Vector Graphics (www.w3.org/TR/SVG/) and SMIL, the Synchronized Multimedia Integration Language (www.w3.org/TR/smil20/), there are many industry-specific standards. For example, the HR-XML Consortium has defined a number of XML standards for Human Resources; you can find those standards at hr-xml.org.
Finally, for a good source of XML standards, visit the XML Repository at xml.org/xml/registry.jsp. This site features hundreds of standards for a wide variety of industries.