For a while now, Facebook have allowed you to change the URL of your profile or fans page to what is known as a vaniety URL.
For example: http://www.facebook.com/yourname
To change your URL is a simple process, just login to Facebook and go to http://www.facebook.com/username and follow the instructions.
More details can be found in this article: http://blog.facebook.com/blog.php?post=90316352130 so please read them before going ahead and changing your URL.
There are slightly different rules with changing URLs on Fan Pages to try to prevent URL squatting. However, if you are planning to use a Fan Page for your business, changing the URL is worth while as it can help with SEO.
Some examples of Fan Pages with a vanity URL:
http://www.facebook.com/ExplorerTravel
http://www.facebook.com/LandscapesOfEngland
