Social media is helping the cash registers ring this holiday season.

A recent study by comScore found that 28 percent of online holiday shoppers have been influenced to make a purchase by social media. Consumer-generated product reviews led the list as the most influential, followed by expert product reviews, Facebook fan pages, Facebook friends' recommendations, tweets from a brand on Twitter, and finally, tweets from friends on Twitter.

Brands are certainly realizing the effect of social media on the bottom line. Earlier this month, Dell attributed $6.5 million in sales to its use of micro-blogging site Twitter – combined with efforts on Facebook, MySpace and YouTube.  To top it off, the New York Times referred to this year’s holiday as “America’s First Twitter Christmas.”

If you’re thinking about entering into social media, or you’re already doing so for your brand, remember that consumers have the right to say whatever they want to about your product – and really, that’s not a bad thing. Wouldn’t you rather hear a person’s opinion of your product, rather than have them talking offline behind your back? By engaging with customers through social channels, you give them the platform to discuss your product – good or bad – and give your company access to research that might have otherwise gone unnoticed.

Encourage customer reviews, engage your online audience with discounts, make your information easily shareable, and be accessible to answer questions and/or complaints.

How are you using social media to reach out to consumers this holiday season? What examples have you seen of great uses of social media? Have you seen any that have completely missed the mark?