A few years ago I released HostDB, my simple system for generating DNS domains. The LISA paper that announced it was called: HostDB: The Best Damn host2DNS/DHCP Script Ever Written.
I just released 1.002 which adds some new features that make it easier to generate MX records for domain names with no A records, and not generate NS records for DNS masters. Other bug fixes and improvements are included.
HostDB is released under the GPL, supported on the HostDB-fans mailing list, and supported by the community. This recent release includes patches contributed by Sebastian Heidl.