After Amazon, eBay was the second most often visited site, followed by Dell.com, the Hitwise survey found.

Dell, which didn't make the top 10 list in 2003, attracted more traffic than the sites of the nation's biggest traditional retailers, including Walmart.com, Bestbuy.com and Target.com.

But those retailers also made impressive gains in cyberspace, with Walmart.com and Target.com posting 18 percent increases in 2004.

Meanwhile, e-commerce tracker ComScore Networks said overall online holiday sales grew by about 29 percent from a year ago to about $15.8 billion during November and December.