Nancy

Server implementation using the Nancy framework (www.nancyfx.org).

Nancy is a lightweight .NET web framework inspired by Sinatra.

The index.htm is server up from the HomeModule class, and the API used by the backbone app is implemented in the TodoMVCModule.
The todos are simply stored in memory. Nancy doesn't care about persistence, so adding e.g. Mongo persistence wouldn't show much Nancy (apart from maybe how it handles DI).

To build and run visual studio is required. Using visual studio it should build and run out-of-the box except for deleting todos which requires tinkering with netsh to make Windows allow the DELETE verb on localhost:51216.
Command line build is also an option using MSBuild.
This should run without any problems on AppHarbor (www.appharbor.com).