There is a little problem with my mango :(
Every time I try to add a reference to a Web Service I end up with an empty Reference.cs.
Sad. The bug has already being sent to MS see: https://connect.microsoft.com/VisualStudio/feedback/details/624612/add-service-reference-service-proxy-class-gen-tool-bug
The workaround:
Use the SlSvcUtil.exe that can be found at:
C:\Program Files\Microsoft SDKs\Windows Phone\v7.1\Tools
Just call it with like:
SlSvcUtil.exe http://localhost:50002/DBServices.svc?wsdl
NOTE: For some reason I have found that the 7.1 version of the tool crashes with a StackOverflow.
If it happens to you just use the 7.0 version