Somehow, 3 gigs in a row, I've found myself involved with dynamic #DNS infrastructure.
The pattern is always the same; there is a database of some sort, and then #bind or #powerdns serving results. Updates happen using a custom web interface or home-brewed web API.
But - we have a standard for dynamic DNS updates! It's called #rfc2163. Why aren't we using it? Because DNS is less dev friendly, I guess?
So I wrote Duppy: https://github.com/pagekite/duppy - a reusable #RFC2163 DNS update server.