I also highly recommend checking out ServiceStack, it's a config-free web service framework I started that lets you easily and rapidly develop web services with very little friction.
It provides an expressive friction-less environment as you're able to develop web services by using you're own POCO C# DTO's which also encourages best-practices web service development since you're easily able to create more batch-full, coarse-grained APIs.
It's aims to be more productive by closely fusing C# with HTTP where all C# objects returned get automatically serialized to the requested format with (XML, JSON, JSV, CSV, SOAP 1.1/1.2, HTML) supported out-of-the-box. C# Exceptions also get automatically serialized for you making the tedious things effortless.
One of the major benefits is not needing to be concerned with external formats and endpoints (which are taken care by the framework) and you're left with developing your logic in a clean-room, auto-wired and highly testable, DDD-like IService class.
