More and more U.S. retailers have fan pages on social media sites, eMarketer reported Wednesday.

Facebook is the top choice for these retailers, according to a study conducted by Internet Retailer and Vovici in August 2008.

About one-third of responding businesses said they had a fan page on Facebook, 27 percent on MySpace, while only about one-quarter had one on YouTube.

According to a study by Rosetta (formerly Brulant) in September 2008 targeting U.S. top 100 online retailers, 59 had a fan page on Facebook, up from 30 in May 2008. Those who have added Facebook pages since May include Best Buy, Toys “R” Us, Kohl's and Wal-Mart, eMarketer reported.

“Social media sites continue to be an important source of community connection, and savvy retailers are reaping the benefits of Facebook's rapid extension into new demographics, such as Gen X and seniors,” Adam Cohen, partner with Rosetta's consumer goods and retail practice, said in an interview with eMarketer.

However, “It's important that retailers don't just slap up a page because everyone is talking about Facebook. An effective presence requires that you carefully consider what your customers are looking for, what you would like to communicate, and what role a fan page should play in your overall online strategy,” Cohen added, according to eMarketer.