Add jquery-treeview (http://bassistance.de/jquery-plugins/jquery-plugin-treeview/) to your rails app.

Requires Rails 3.1.

To install:

1. Add to your Gemfile, in the :assets group:
  gem "jquery-treeview-rails", :git => 'git@github.com:kclair/jquery-treeview-rails.git'

2. Add to your application.js file:
  //= require jquery_treeview