TorqueBox Lite is a web-only, smaller cousin to TorqueBox. It doesn't support scheduled jobs, messaging, services, or any of the other non-web features of TorqueBox. What you do get is the great web performance of TorqueBox in a smaller package. Now that Heroku officially supports JRuby, it's easy to choose TorqueBox Lite as your web server.
Make sure you've created a JRuby application on Heroku and then simply add 'torquebox-lite' to your Gemfile and Procfile as shown below.