Over the last week I moved http://www.thebigeat.com/uk from PHP to Rails. That uses Geocoder, Carrierwave, Stripe, gmaps4rails, FriendlyId and Rakismet. I use Gems because they do what I need to be done. When they don't then I roll my own - I used to use Devise, but hacking around it just became inflexible and more work than my own.