There are a lot of sites that you can use to find your IP address, but many of them like whatismyipaddress.com flood you with advertisements and popups. This-IP.com is one site that you should always keep in the back of your mind. There are no advertisements which is obvious since the screenshot above is of the COMPLETE site.
The two navigation links at the bottom, which I have taken the liberty to circle, allow the user to either see more details or less details. When viewing More Details you will see your IP Address, IP Name, Remote Port and Browser. When viewing No Details it will only show you a text file with you IP address — plain and simple with no formatting which results in a page that is less than 15 bytes in size!
I am not normally one to talk about these kind of sites but I think this one is worth bookmarking.