SOAP, Web Services, Java, and C#
Messing around quite a bit with SOAP, web services, Java, and C# lately. What I've been doing is creating a common framework of testing utilities for QA with everything exposed as a web service. The set of services is not totally defined, but will likely include core tools such as an XML Comparison Engine, writing results to Mercury Quality Center/Test Director, mock services of web services in the company's SOA, etc...
With Tomcat, all you need to do is put a Java class in the /webapps directory and rename the name from .java to .jws. Tomcat takes care of all the SOAP and web service stuff. Pretty neat stuff. For example, here is a simple XML Comparison Engine