rofldns is DNS server which is a fork of loldns, itself a fork of djbdns. It inherits all the good stuff from loldns, which includes multiple listening IPs, running as a service rather than under daemontools, and some other useful patches, but in addition builds under automake and trivially makes an RPM.
This is a simple Python script to register your dynamic IP address using the NIC V2.0 protocol. It aims to be fully compliant with the dyndns client specification. It currently supports all options and recommendations as of June 12, 2001, including myDynDNS custom domains. The script is very easy to use and supports multiple methods for determining the external IP address.
Microbrew Message Center is designed to be an immensely scalable mail platform supporting multiple users, multiple domains, and multiple mail servers. It is akin to iPlanet or post.office but is not as complex and uses open source software to perform mundane services such as Web and mail services.
sheerdns is a master DNS server whose zone records are stored on a One-Record-Per-File bases. Because of this, it is the simplest of any DNS to configure, the easiest to update, and the most efficient for networks that experience a lot of updates (for example master servers for dynamic IP address ranges). You never have to restart it; any updates are available immediately without having to notify the sheerdns process.
Ruby Dynamic DNS Client is a highly customizable, easy-to-use dynamic DNS update client. It features the ability to retrieve the IP address (using ifconfig or over the Web), support for various dynamic DNS services (dyndns.org, changip.com, cjb.net), support for multiple languages (Dutch, English, German, Italian, Romanian, Spanish), and a config file generation script.
popdns is a small daemon that aims at simplifying the use of roaming machines by allowing them to dynamically update their DNS entry using (nearly) any POP3-capable email tool. After having configured a new email source (with the POP3 protocol), users are authenticated using their system password and popdns automatically updates their DNS entry with the IP address of the connecting machine.