In terms of a client testing application, I had a similar problem. I couldn't find a tool that I could use to quickly test data going in and out of the web services I was creating/using. So I created my own tool using C# .NET. It's essentially a client application that you can use for GET, POST, PUT, and DELETE queries on rest services.
The software is called REST Scratch Pad. It lets you enter the data to send to the REST service and view the results of queries along with their headers and response times. It will handle basic authentication and will remember the URLs you've used in prior sessions (to avoid having to re-type long URLs).
The current version is free. The next version will use a newer version of .NET and cover more authentication methods.
REST ScratchPad
