GnuDIP is a application designed to allow an ISP to publish a DNS hostname for a customer without having to assign a static IP address. Customers can maintain the address information via a CGI on the ISP's website. For those who are familiar with the dyn.ml.org part this is a simple replacement package.
Dents is a from-scratch implementation of the server side of the DNS protocol, sharing no code with any other project. Among its several features are compatibility with named, a modular driver system and an extensible control facility which allows the administrator to control the running server.
CustomDNS is a modular DNS server written in Java. It's based on Brian Wellington's dnsjava pacakge, but it adds support for virtual hostnames, SQL databases, and dynamic client updates. You can use CustomDNS out-of-the-box as a clone of ml.org/dyndns.org, or you can use it to develop custom DNS applications.