This is a simple Rails 3.1 app that uses parse_resource for model persistence and includes a simple auth system that's based on this Railscast.
If you already use Parse, this Rails app is a really quick way to give your app a web presence.
git clone git@github.com:adelevie/parse-rails-boilerplate.git
cd parse-rails-boilerplate
Change application names where necessary, if desired.
bundle install
Create a parse_resource.yml file. Instructions here.
rails s and enjoy.