Two of my co-workers, Henry Adam and Sai Kolla, turned me on to some new tools for testing Web Services. The first tools is called soapUI. It is an opensource project for testing SOAP calls and generating SOAP envelopes. They also have plugins for Eclipse, IntelliJ and NetBeans.
They also showed me a full blown testing tool called Lisa. This is not an open source tool, but is free to the first 50,000 registered users to download the tool. Lisa will allow to do assertions.