Smashing, the spiritual successor to Dashing, is a Sinatra based framework that lets you build excellent dashboards. It looks especially great on TVs. Use premade widgets, or fully create your own with scss, html, and coffeescript. Has a REST API to push data to the dashboard. Drag and drop interface for building a dashboard.
Install the gem. Run it to create a new dashboard ("project"). Run bundle. Start the server for the project.