It would be very useful if CF supported Reverse DNS hosting capability.
Basic support of the ip6.arpa and and in-addr.arpa. namespaces would mean I do not need an alternative DNS provider to just host reverse DNS. You would likely cause a significant increase in DNSSEC deployment on reverse DNS if you hosted reverse DNS zones.
As an added feature, linking forward and reverse DNS would mean that when I create a forward entry for origin.example.com, you could populate the linked reverse entry automatically (similar to how Windows DNS servers can work).
Obviously most of the UX would be meaningless for reverse DNS zones, and would be greyed out.