Twitter-and-MongoDB is a project mainly written in RUBY and JAVASCRIPT, it's free.
Playing around with Rails MongoDB and Twitter
I'm not really sure about what I'm doing here. Mostly playing with Rails, Twitter and MongoDB. Spending one more late night up and coding.
More time off means more time to study new stuff.
The app requires MongoDB, rails 3.0.5 and ruby 1.9.2.
So just run MongoDB after installing it. Bundle install and you should be ready to go.