The Telerik JustDecompile tool is great for helping troubleshoot build issues. Was assisting someone who was running into a WCF service error. The service method reported in the error was nowhere to be found in the codebase I was looking at. I verified that by using JustDecompile to look at the compiled code in one of the related DLLs on the test server. Turns out the client app he was running, was a newer version, while the service it connected to ran the old code.