If you use Facebook you'll probably be aware that they recently allowed ther users to register a 'vanity URL' (username is their name for it). Bigwigs have always been able to boast of an URL such as facebook.com/u2 , but this feature has been opened-up to (almost) everyone else.
The value, especially if you're a big user of facebook, is simply to be able to send people to your profile with an easy to remember URL. So I can now say 'check me out on Facebook at www.facebook/com/stevemccabe'.
But to fully utilise this feature, you'll need to make changes to your Facebook privacy settings. Because it's no good boasting of your new FB address if, when someone goes there, there's no infornation showing about you. So in your Facebook privacy settings, make sure you enable the Search Visability to 'Everyone'.
This way your new Facebook URL will say at least something about you, especially for non-Facebook users visiting the URL.