Dynamic DNS

DirectUpdate
Win32 (95/98/Me/NT4/2000/XP) dynamic DNS updater that runs as an NT service with remote administration.
http://www.directupdate.net

DynSite for Windows
Shareware DynDNS Client for Windows platform
http://noeld.com/download.htm#DynSite

No-IP.com Update Client
Dynamic Update client for No-IP.com. Mac/Linux/Windows
http://www.no-ip.com/downloads.php

SiteDevelopers.com
Windows Dynamic DNS Client supports many dynamic DNS services. Program is offered in a Windows service, desktop client and lite version.
http://www.sitedevelopers.com/

StaticCling client - StaticCharge.
Clients available for MacOS, OSX, Windows, and Unix desktops.
http://www.staticcling.org/clients/