Perhaps I'm missing something, but what exactly is appealing about this service and/or is new and innovative? It's trivial enough to put a web interface in front of BIND or djbdns to replicate this behavior to where I'm trying to understand why this got ranked highly? I am by no means bashing the creator of this service nor the service itself - I'd just like to understand what additional value is being provided here that does not already exist?
You boot up an ec2 instance and want to give a domain name to a friend that isn't 100 characters long. How much effort does it take you setup your bind solution? Particularly if you've never setup dns before. Can I do this given that I'm not running any other servers? The popularity of dyndns should give you a sense of demand.
You say it's so trivial yet you didn't include a link to the one you just set up to prove your point :p So not quite that trivial, and that is often enough.
Quite often it is useful to be able to do something easily and quickly that you could have done before with more effort.
