Thanks to your comments, emails, tweets, and links to your own blogs, we have revised the paper. First, we have now systematically covered the top 50 economics blogs and include in our dataset all of those that linked to a paper in RePEc. As a result, we now report impact findings for Overcoming Bias  and Baseline Scenario  as well -- two very popular economics blogs.
Second, we added a section regarding influence on policy, which is largely based on the feedback we received from you. We'd like to hear what you think.
Finally, in the concluding section, we speculate that there may be an undersupply of good economics blogs. This is based on the evidence we present on the positive externalities of blogs and the costs to blogging. We can certainly think of at least a few economists that we'd like to read on a regular basis - and not just in an academic journal.