E-Commerce is what has caused the internet explosion that made the Internet what it is today. One of the most desired features of a quality web portal is to be able to sell goods., be it products, services, mementos, etc, the ability to sell on the web is still the main reason for having a website today.
Features include:
categories, products (list and details), mini cart (with integrated controls), full shopping cart (including multiple ship/bill to addresses/recipients), reviews (including a review admin for approving reviews), order history (customer and admin viewable), and provider based gateways.