Me too.  I tried developing some Vonage stuff myself, but could not find any support from them.  I know others have developed applications that work with Vonage, but I don't know how they managed.

Example:  I developed a widget that will make outgoing calls using their 3ppc (Third Party Call Control) interface.  It works fine when run locally, but their site does not have a crossdomain.xml file at the root.  I tried various ways of contacting them to request this, but I get either no response, or some canned response that's completely inappropriate.