GitHub User: fortuity
For details that are not covered in the RailsCast, take a look at the open source example application for a Rails Membership/Subscription/SaaS Site from the RailsApps project. It comes with a tutorial that goes into detail about how to integrate Stripe with Devise, shows how to use Stripe webhooks, and explains the implementation in detail.
I put together a Rails 3 example app (with a detailed walk-through tutorial) that shows how to use Mongoid with OmniAuth (plus optional RSpec, Cucumber, and Haml): https://github.com/fortuity/rails3-mongoid-omniauth. It goes into more detail than the Railscast for those who need a full starter app.