A partial clone of the note-taking app Trello, built using Ruby on Rais and Backbone.js. It's not particularly polished, particularly in terms of css design. But it has, I think, some interesting logic to manage Trello's drag-and-drop functionality. The drag-and-drop animation is managed by jQuery UI, but there's still interesting work required in keeping track of the order of the items (both client- and server-side).