MongoDiplom is a project mainly written in RUBY and JAVASCRIPT, it's free.
== MongoDB Rails 3 App Skeleton
This is just a sample app skeleton for an application with Rails 3, MongoDB, and MongoMapper.
The relevant files are:
To start the server: rails server
To start the console and play with the user model: rails console
All of this assumes that you've installed Rails 3 and have a mongod process running.