The custom prestige domain is a way to reach a larger demographic of people. Your domain is a site that you can promote through sites such as Facebook, Twitter or MySpace. You could also let people know about it through word of mouth, flyers/mailers or you could even pay to post your domain info. in a shopper, newspaper, etc... All it really does is give you another marketing tool for drawing in people to SFI and Tripleclicks through means other than direct signup.