How do I get the IP external to my local network given by ISP?

So you have a local network on the 192.168.*.* subnet. My router is somewhere on 192.168.1.1 or 192.168.1.254. Now what am I known as on the internet? What is my IP for the internet, ie what is the dynamic IP that my ISP has given me? HERE IS THE ANSWER, once you have this you could script things ....