Amazon sells a nice little set top box they call the FireTV. It runs android 4.2 with their own modifications. They also sell a game controller for it and they let you side load apps. I was able to install the current stable version of retroarch just fine using adb, but it would be awesome if you had it on the Amazon app store.
Here’s a link to the device page: http://www.amazon.com/Fire-TV-streaming … rds=firetv It’s stripped down brother called the FireTV Stick: http://www.amazon.com/Amazon-W87CUN-Fir … rds=firetv And the developer portal for the Amazon app store: https://developer.amazon.com/appsandservices