Seth's Blog - Seth Godin is the one time most popular blogger on the face of planet earth...might be worth checking out his stuff. He writes on business theory, particularly on the marketing side of the equation, some pretty good stuff.
Farmstrong - JD Walt is one of those people who personify profound. His whit, humor, and deep thinking are bound to make you a better person. He is also my boss. Did I mention he's also very good looking?
upSIDEdown - Paulo Lopes is a guy who you should probably begin to read now, and in 15 years when he literally has taken over the world, you might get to keep your job.
(He just started blogging last week, but I'll put him up here just on potential)
Recliner Ramblings - I've known Mike for a number of years now, and he never fails to write a thought provoking piece. Former co-editor of an online magazine, Mike's posts continually create a tension within my head that makes me a better person.