Do you use Groupon or Living Social? Do they send you a ton of emails about stuff you don't want?
We wanted a site that would only show people discounts on the things actually care about. When users register they get a personalized store that pulls in all the best discounts on the web - clearance sales, promo codes, refurbished items etc.
We sell daily deal type discounts targeted by user info (gender, location, age, interests) so advertisers get people that become repeat customers.