Cross Selling | Up Selling

Retailers do this all the time in shops so why not online, cross selling products or even up-selling can be done, in its simplest form you might have "Similar" or "Related" items showing underneath a product, this can be expanded to also show "related" or "Similar" items in the checkout, maybe you are selling knickers and can push a matching bra, or an electrical item that needs batteries.

All of these things can be done, displaying products to your visitors whilst they are browsing and buying, it can also be done after a customer has purchased, keeping track of customers orders and sending follow-up email marketing campaigns with similar or related in conjunction with promotions and offers items can often bring customers back time and time again.