John Gotze has written a SOAP interface to the search function for Denmark's reference profile (often called an interoperability framework). Here's the WSDL file, here's the code for a SOAP::Lite example client, and here's the client in action. If you don't speak Danish, this won't be so useful as a reference profile, but its a great example of how you can do some simple things in a few days that provide some interesting possibilities for interoperability. Web services aren't about the big thing, they're about lots of little things, arranged correctly.