Facebook started allowing users to choose their own URLs to access their Facebook pages, e.g. mine is http://www.facebook.com/improbulus - before that, URLs just involved unmemorable letters / numbers.
But it's first come first served so you'd best get in there fast if you haven't already. It's not compulsory for you to pick a username for your web address, you don't have to if you don't want to, but it may make life easier if you do it (also, note that people who signed up for Facebook only recently may not select a name till 28 June 2009 - see the Facebook username FAQs).
When you login you're supposed to get an alert popup offering you the option to choose your URL. I didn't get a popup, but thanks to Mark Ng and Rachel Clarke I managed to grab my URL anyway.
Here's how to select your Facebook username / vanity URL:
- Login to Facebook.
- Then go to http://www.facebook.com/username/ - important: do NOT change "username" to your own username, which was my own mistake - it literally is "username", just click the link I just gave.
- Select your username, if it's not been taken already - else, pick another one.
- That's it!