What is a "Successful" Blog?

Recalling all of the usual advice we've heard over the last few years, Entrepreneur.com lays out the three ingredients to become a "successful blogger." They are great content, regular updating and your own distinct voice. But the real question is just what is "a successful blog?" It really varies depending on your goals. A blog can have two readers and be successful if you build a sustained dialogue with these constituents. There's no one vanilla answer to this question.