I agree, soapUI is a very nice open source product for testing both
SOAP and RESTful web services. You can construct test cases/suites in it, and even use it to act as a server for mock-requests (they offer a commercial alternative that has a few more bells-and-whistles). In many of my examples in the book I have soapUI integrated in with
ANT for testing of the example services (i.e., you run an ant target that will automatically launch soapUI along with the appropriate project).