At Overstock, we use REST Web Services created using the RESTLET project. As I continue to work with REST, I sometimes feel the pinch of good tooling support. This especially is surfacing with the lack of a simple testing tool for RESTful webservices (both for dev and QA testing). With the RESTLET API, I can easily develop the Web service. However, when it comes to just checking how the WS is functioning, I find it difficult to do the same without creating a java client and/or unit tests. On the SOAP front, a fantastic tool introduced to me by a good friend of mine, Dave Stockmann, was simply a developer and tester's delight.
The tool SOAPUI, faciliated the generation of a testable graphical interface from a WSDL. Sure we could code the test client in java for a REST WS and provide a web page to make the REST calls, i.e., POST, PUT etc but if the same could be auto-discovered and provided via a tool like SOAPUI, it would make developing with REST Webservices so much pleasurable.
The primarily lack of tooling for REST is IMHO the lack of maturity of a definition format. WADL from Sun looks promising and I hope to look further into it. I am particularly impressed by the rest-api-code-gen project and their live demo application.
I hope the rest-api-code-gen folks take the project further in that apart from generating a WADL and client code, provide a SOAP UI like interface when provided a WADL to invoke the different operations.
If nothing surfaces soon, I might get started on a SOAPUI equivalent called RESTUI ;-)