My Facebook ID is to help you find your unique Facebook ID, a useful tool for Facebook developers, enter your
facebook profile url
for example: "facebook.com/screenname"
It's simple, this site does exactly what it says, you login to your Facebook Account (if you're not already), and it will tell you your User ID.
Well that is a good question, as a Facebook Developer it is often frustrating to find your own, or another user's ID when you need it. So this site aims to give developers an easy way to get their current Facebook ID - or any other person for that matter.