Wouldn't it be cool to get to your profile page when you type www.facebook.com/YOURNAME
Facebook launched this feature Starting at 12:01 a.m. EDT on Saturday, June 13. If you haven't personalized your name yet, well your exact name may not be available so hurry!!
Facebook lets you have only one username for your personal profile. Once you have claimed a username by clicking the "Confirm" button after checking for a username's availability, it is not possible to transfer your username to a different account on Facebook. Even when an account is removed from the site, its username is not available. Facebook does this for security reasons. You should make sure it is something you like and that it’s appropriate for friends, family, co-workers, and anyone else who might use it to find you.
Keep in mind you will only be able to change your username once, even if you misspelled your username.
HOW TO CHANGE YOUR USERNAME ON URL?
You can change your username from the Settings tab of the Account Settings page. Scroll down to "Username" and click "change." Then follow the on-screen directions.