Todd And Power 150
This is a really cool site that ranks the top 150 marketing blogs! 150?! The marketing blogosphere is enormous I tell you! This ranking uses several objective measurements like Google Pagerank and Technorati, as well as a subjective vote by the owner.
The Viral Garden
A weekly ranking of the top 25 marketing blogs using data from Technorati. I tend to agree with this ranking more.
Cool Marketing Stuff
The best 7 marketing blogs. Only the greatest make this list.