Catalog - The online store feature allows you to manage a catalog of items, sponsorships, and downloadable documents (PDF, Word documents, videos, etc.) and allow members and/or the public to purchase them. Items can have photos, and can have additional attributes (like t-shirt sizes)
Online Payment - If you have a credit card merchant account or PayPal account integrated with your MMS account, it will automatically will be configured with the store.
Member/Non-Member Pricing - offer discounts to members
Inventory/Availability - The store module also includes inventory tracking as well as an available/unavailable checkbox.
Tax/Shipping - options for computing tax and shipping are available as well.