This is a question lot of e-commerce project managers ask themselves keeping in mind due to availability of search engines people finding them does not remain a big issue. The Biggest problem they face is deriving the right potential traffic to the site. In series of post i have been making for e-commerce site owners another idea with potential to excellence is to attract tie up with loyalty programs especially the one run by credit card companies. Users which have been accumulating loyalty points are encouraged by banks on every statement to redeem points if you as an online retailer can come up with an exclusive agreement with banks for exchanging those points for credit on your site you can actually attract spend from these customers for other items available in your store. Generally its seen people dont mind shelving off 40-50% of cost on an item if rest is covered by the loyalty points. So you can have these people constantly surfing your site looking at items available.
Rest i believe is dependent on pricing and other factors. So go and mull out an marketing alliance with these credit card companies and see it it works out for you.
Will be more than glad to help you make a road map.