Time was, small-business owner Evan Prytherch considered eBay (EBAY) capable of performing e-commerce magic. Prytherch would list his entire music-accessory inventory on the auction Web site and within days it all seemed to disappear. Sold.

But in recent years, much of that magic is gone, Prytherch says. Shoppers are simply not buying all the inventory anymore. Some items languish without a single bidder. Many shoppers opt for other sites including Amazon.com (AMZN), use sophisticated search engines such as Google (GOOG) and Yahoo! (YHOO), or head to store sites directly.