I'm looking into the API for the Hi5 social network and unfortunately found some WSDL. They also have a REST API, but it's documentation appears auto-generated from WSDL that nobody actually filled in. Somewhat useless.
Normally I wouldn't post about WSDL, but I couldn't pass up the irony of the WSDL documentation for the authentication service API having an HTML form describing how to authenticate the user. If that's not irony, I don't know what is.