eBay, the online auction powerhouse, is preparing to celebrate its 10th anniversary next week. The Economist magazine features eBay on the cover this week, referring to the company as the “darling” of e-commerce. Yet, while eBay is clearly the biggest auction enterprise here in the U.S., there are other competitors vying for a piece of the auction action. As the Economist article notes, Yahoo! auctions are the marketplace of choice for Japanese consumers, and the growing Amazon auction audience may also prove to be a formidable force in the future.

Our surveys now show that one in four internet users have tried their hand at online auctions, and that the absolute number of online auction participants has been growing along with the overall internet population. We have been tracking online auction use since we first started gathering research in 2000. Since that time, the number of online auction users has more than doubled. While roughly 13 million American adults (or 15% of internet users) had participated in an online auction in March 2000, about 32 million (24% of internet users) reported doing so in our February-March 2005 survey.

Online auctions are still generally the province of internet veterans and those with higher levels of income and education, but all users under the age of 50 are equally as likely to have taken part in online bidding. However, eBay and other auction sites still appeal more to wired men than women: 30% of male internet users have participated in an online auction compared to 18% of female users.