Mobile Phone Number

It isn't hard to do, and it make "business intelligence" sense.

Next time a customer orders, online, via a call center, or in-store, ask the customer if s/he is willing to provide a mobile phone number.

From a modeling standpoint, the attribute tells you that the customer is probably "less interested" in old-school marketing (print, catalogs).  Instead of the customer being pelted with eighteen catalogs a year, you tone it down to five or six, saving a ton of money in the process.

Customers who volunteer a mobile phone number are more likely to generate demand "organically", i.e. without the aid of catalog marketing.  The customer is more likely to fall into "Jennifer" or "Jasmine" categorizations.