I attended a interview recently for which the pre-requisite was to develop a chat application using WCF as part of a code challenge. The requirement was quite simple, so instead of taking the usual route of creating a WCF service and adding its reference to a client application, I decided to hand code everything without any configuration or service references!
Of course the assumption here is that the service and client applications are owned by a single company/team so that the contracts can be shared between the service and client.
My Code Catalog 