Opensource .NET and Mono REST Web Services Framework

Service Stack is an open source .NET Mono REST Web services framework. Check it out.

ServiceStack is a modern, code-first, DTO-driven, WCF replacement web services framework encouraging best-practices for creating DRY, high-performance, and scalable REST web services.

By using ServiceStack, developers can easily developed WCF REST web services target .NET and Mono framework.

Check out full details here:
http://www.servicestack.net/