Founded in 1999 by Nick Swinmurn, Zappos.com has thousands of shoes at discount prices. Their easy to navigate website is top-notch.
They believe that the speed at which a customer receives an online purchase plays a very important role in how that customer thinks about shopping online again in the future, so they have put a lot of focus on making sure the items get delivered to their customers as quickly as possible. In order to do that, they warehouse everything they sell, and unlike most other online retailers, they don't make an item available for sale unless it is physically present in their warehouse. Their prices and selection are unparalled.