Anteater is a functional testing framework for testing HTTP and SOAP based applications. It's a very useful tool especially when the application you're testing makes HTTP/SOAP requests back on the client. This is the case with higher level SOAP-based protocols like ebXML or BizTalk.
Anteater is based on the httpClient testing framework from Tomcat 3.x, and was heavily modified to provide unified matching on outgoing and incoming HTTP requests.
Anteater is an open source project and can be obtained from http://sf.net/projects/aft.