Macintosh Dynamic DNS Client - http://www.sentman.com/dyndns/ Program that works in conjunction with Dynamic DNS Providers to send the IP Address to the provider whenever it changes.
DynSite for Windows - http://noeld.com/download.htm#DynSite Shareware DynDNS Client for Windows platform
SiteDevelopers.com - http://www.sitedevelopers.com/ Windows Dynamic DNS Client supports many dynamic DNS services. Program is offered in a Windows service, desktop client and lite version.
DirectUpdate - http://www.directupdate.net Win32 (95/98/Me/NT4/2000/XP) dynamic DNS updater that runs as an NT service with remote administration.