whatismyip.org isn't terribly reliable, though (It's been down for days at
a time in my experience), so I wouldn't use it in automation. OpenDNS
provides http://myip.dnsomatic.com/ (designed for use with apps for their
DNS-O-Matic DNS update synchronization service) to the same ends, and it
has all the reliability of an OpenDNS service (nobody has ever seen it go
down, to my knowledge).
