ISPMan is a system to design massive ISPs using LDAP as the backend.
ISPMan provides a web front end and a command line interface to create virtual domains and manages users, dns information, email infos and httpd setup data for these vhosts.
XMDNS is an extensible DNS management scheme that uses XML to store data. It features easy manipulation of views (or split horizon DNS). There is also support for hand-crafting records for situations where complicated rules must be enforced.