ez-ipupdate is a small utility for updating your host name 
if you are using any of the following dynamic DNS services:

	http://gnudip.cheapnet.net (GNUDip)
	http://www.dhs.org
	http://www.dyn.ca (GNUDip)
	http://www.dyndns.org
	http://www.dyns.cx
	http://www.easydns.com
	http://www.ez-ip.net
	http://www.hn.org
	http://www.justlinux.com
	http://www.ods.org
	http://www.tzo.com
	http://www.zoneedit.com

It is pure C and works on Linux, *BSD and Solaris.

The key features are: support for multiple service types, daemon 
mode that monitors your IP address and only sends updates when 
your IP address changes.

WWW: http://www.ez-ipupdate.com/