windows - How do I find out what my external IP address is?

Question

My computers are sitting behind a router/firewall. How do I programmatically find out what my external IP address is. I can use http://www.whatsmyip.org/ for ad-hoc queries, but the TOS don't allow for automated checks.

Any ideas?

Answer 1

http://ipecho.net/plain appears to be a workable alternative, as whatismyip.com now requires membership for their automated link. They very kindly appear to be offering this service for free, so please don't abuse it.