My understanding is that numbers also play a more important role in communication and symbolism in many eastern cultures, and in a much more significant way than "lucky 7's" or "Friday the 13th" does in the west. Many westerners, while being aware of number symbolism, look at the associated meaning more in the light of superstition, ie walking under a ladder.)
In China, 8 is associated, more or less, w/ good fortune, 888 is very, very good fortune. 6's and 9's are also highly regarded. 168 is strong. Businesses will pay/have paid big bucks and premiums for the rights to telephone #'s, good office addresses, as well as, domains w/ good # combinations. 888.com has got to be bringing in millions in the Asian market. Hotel rooms w/ 888, 168, etc are requested by guests. How many people in the west ask if hotel room #777 or 107 is avail? 13, does however, have more of a stigma- most highrises skip floor 13, jumping from 12->14, for instance.
Other, more obscure, areas where pure NNN domains come into play are w/ union #'s, ie, IATSE local 600, highways and interstate #'s (particularly ones that locals commonly refer to as a number), product designations and street addresses. If your business, (think restaurant, beauty salon, boutique), was on a well known, prestigious street, ie Wall St, Madison Ave, Michigan Ave, Rodeo Drive, etc. a website in conjunction w/ the business name, w/ the street address, (ie Cafe 909, or simply 909) could be a strong branding tool, if developed and marketed properly.
