The EBay Way (Robert Cringely) -- "In terms of sales, the company is comparable in size to Amazon.com. But Amazon's sales are primarily composed of goods while eBay's sales are composed almost entirely of commissions -- commissions that average around five percent of the value of goods bought and sold. So while Amazon and eBay are both around a billion in sales, eBay actually represents more than $20 billion in economic activity."