In an email to motivate people to sign up for their new feature I like how Alltop positions the situation:
One ramification of this is that people will grab “vanity” accounts like their names, companies, and products. We wanted to let you get the first shot at doing this before we open the floodgates.
Oh no, I might not get http://my.alltop.com/mattgoyer, I better sign up now! :)