Here are some useful websites using which you can know your own IP Address and if you have the IP address of other then you can find his location also.
My Ip Test.com
This website provides a wide range of geo location services. You Just need to put the IP Address (it will catch your IP address automatically) to know the location of the IP address user. This Website will not only tell you the location but will also show you on Google MAP.
IP Lookup
IP Lookup is another web service which gives you access to know the location of any IP Address. You dont have to put your IP address to know you location and other data. Just open this website and it will automatically show your IP Address location data with Google Maps. But if you know the IP of other guy, just put the IP and get his location and other (limited) info.
IP Address Location
This is yet another IP Address Location tracer website which not only tells you the location (like country, city) and ISP info but also tells you the information of your Computer that which Operating System you are using, which browser you are using etc.
What Is My IP Address
What is my ip address is easy to remember website using which you can know your IP address and also can get the information of Other IP Addresses