Shareholder activists use a variety of tools to combat lagging companies, such as proxy fights, litigation and so on.

With the growth of social media, we are now seeing new approaches, and one of the innovators is Eric Jackson.

He is using Google (NASDAQ: GOOG)'s YouTube to confront a variety of companies, such as Yahoo! (NASDAQ: YHOO). In fact, he was a key factor in the company's shareholder meeting last year (example here). Keep in mind that Yahoo's CEO, Terry Semel, soon left the company.

Well, according to a piece in FINalternatives.com, Jackson now has his own hedge fund, called Ironfire Capital.

Jackson 's approach isn't completely hostile. In the early stages, he tries to work with a target, but if that doesn't work, he mobilizes the forces of the Internet. And as we've seen lately, that can be quite powerful.

Tom Taulli is the author of various books, including The Complete M&A Handbook and The Edgar Online Guide to Decoding Financial Statements. He also operates DealProfiles.com.