Thomas Erl's SOASpecs.com - A reference Web site dedicated to WS-* specifications, first generation Web Services specifications, and core XML specifications. - http://www.soaspecs.com/
Web Services Specifications - A collection of links to specifications for Web Services at the MSDN. - http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnsrvspec/html/wsspecsover.asp?frame=true