CORBA has IDL; SOAP has WSDL. Developers often ask for similar capabilites for HTTP-based, "RESTful" services. While WSDL does claim support for HTTP, isn't well-positioned to take advantage of HTTP's features, nor to encourage good practice.
wadl_documentation.xsl is an XSL stylesheet that transforms WADL into human-readable documentation, one of many uses of a Web description format.
uri.xsd is a library of XML type restrictions that correspond to different components of a URI, so they can be accurately described (e.g., in a WADL param element).
Feedback is preferred on the W3C http description list.