I second Stripe, Twilio, Tokbox, Dwolla as leaders in good implementation--then add Full Contact, Iron.io, Etsy, Factual and Foursquare to that stack. But defi

I second Stripe, Twilio, Tokbox, Dwolla as leaders in good implementation--then add Full Contact, Iron.io, Etsy, Factual and Foursquare to that stack. But definitely look at the oldest developer areas with eBay, Salesforce and Amazon. They have been doing it a while.