I had a couple of existing domain names transferred from another registrar to be managed by Amazon Web Services' Route 53 yesterday. It didn't offer registration until comparatively recently.
I will gradually transfer all of our, and our client's registrations over as they come up for renewal.
When it is complete I will be managing all our IT requirements with the exception of PCs, tablets and phones we own and broadband subscriptions in AWS.
Amazon Web Services was launched as a limited beta just over eight years ago.