Among the top 100 brands reviewed, Starbucks came out on top with a score of 127, followed by Dell (123), eBay (115), Google (105), and Microsoft (103). Companies were scored based on the level of interaction across 10 social media channels including blogs, Facebook, Twitter and wikis.

The study found that social media efforts tend to build on themselves. "There is an exponential growth in the depth of engagement as the brand extends itself into more and more channels," according to the report, titled www.engagementdb.com.

Companies that scored well generally had dedicated -- if small -- teams focused on social media initiatives. The most successful of these evangelized across the entire organization to gain broad-based support and cooperation. And instead of taking a traditional communications approach based on messaging and talking points, they embrace a conversational mode.

The report sorted companies according to four categories, with "mavens" being the most aggressive brands in social media and "wallflowers" sitting on the sidelines. In between are "butterflies" -- companies that are spread to thin across social properties, and "selectives" -- those that excel by focusing on just a few channels.

Among industries, media and technology companies tend to be "mavens" while financial, food and beverage, consumer products and apparel brands were on the other end of the spectrum -- "which is expected given that companies in these industries are just beginning to experiment with social media," the report states."