http://icanhazip.com/ will tell you your IP.
curl http://icanhazip.com/
I previously did this using whatsmyip.org, but it doesn’t work any more.
whatsmyip.org tells you your IP address clearly at the top of their web page. You can also use this tool from the command line by requesting http://automation.whatismyip.com/n09230945.asp. Here are a couple of examples using wget or curl:
wget -q -O - http://automation.whatismyip.com/n09230945.asp
curl http://automation.whatismyip.com/n09230945.asp ; echo
The curl example seems to add a newline at the end, while wget doesn’t.
