I've developed an application that works as a SOA gateway for HTTP. Actually I've published v.1.0.3. The original project home is at http://www.codeplex.com/msservices 

If you are interested you can find the source there too.

With this application you can call database SPs like;
and retrieve Excel output (the output varies depending on the extension)

I am at mertsakarya@hotmail.com please feel free to contact me.