As one whose first "book" publication was a chapbook, I am always interested to see reviewers or blogs paying attention to that method of publication. Here are a couple of blogs I check out regularly for their chapbook reviews.
chap*books, the blog of Plan B Press co-founder stevenallenmay, features mini-reviews of chapbooks from all around the world. His posting of many of the chapbook covers is also a very welcome sight, as many chapbook designers are quite creative with their covers.
Poet Ron Mohring also frequently reviews chapbooks on his blog. Mohring provides lengthier reviews of the chapbooks, along with their covers and a sample poem from each.