1: Go to WWW.whatstheirip.com
2:The site will ask for your e-mail.enter your e-mail and click "get links"
3:Now you will redirected to a page where you'll see some link.
4:Copy one of those links and send them to your friends or person whose IP address u want to known.
5:When the person click's on that link his IP address will be mailed to you instantly.
(Once you have someone IP you can remotely shutdown their computer or port scan them or whatever u want......