Some things your shopping cart might be missing which are non trivial. - Coupons or PROMOS ( X% off, $Y off, stackable) - Persisting a shopping cart betwee

Some things your shopping cart might be missing which are non trivial. - Coupons or PROMOS ( X% off, $Y off, stackable) - Persisting a shopping cart between visits if an user doesn't checkout. - Saving items from a shopping cart to wishing list and vice-versa - Integration with multiple payment gateways but exposing a single interface