Flexible Coupons (pricing rules) with ability to restrict to stores, customer groups, time period, products, and categories.
Catalog Promotional Pricing

Admin Dashboard for Report Overview
Abandoned Shopping Cart Report
Best Customers Report by Total and Number of Orders

Google Site Map
URL Rewrites give full control of URL's
Meta-information for products and categories

Control multiple websites and stores from one Administration Panel
Web Services API for easy integration between Magento and any third-party application
A/B and Multivariate Testing

Batch Import and Export of catalog
Google Base Integration
Downloadable/Digital Products
Advanced Pricing Rules and support for Special Prices (see marketing tools)

Layered / Faceted Navigation for filtering of products in Categories
Layered / Faceted Navigation for filtering of products in Search Results
Product comparisons
Product Reviews

Multiple Images Per Product
Product Image Zoom-in Capability

iPhone Optimized

Multi-Lingual
Support for Multiple Currencies

One-Page Checkout
Checkout without account/Guest Checkout
Shipping to multiple addresses in one order

Shipping to multiple addresses in one order
Multiple shipments per order
Free Shipping

Payment Extensions Available through Magento Connect
Configurable authorization and capturing of funds

Feature-rich Customer Accounts
Order Tracking from Account

Re-orders from account
Downloadable Products
Recently ordered items

View, edit, create and fulfill orders from admin panel.
Create one or multiple invoices, shipments and credit memos per order to allow for split fulfillment