Some top medical bloggers got together and started a new group blog Science Based Medicine:
Science-Based Medicine is a new daily science blog dedicated to promoting the highest standards and traditions of science in medicine and health care. The mission of this blog is to scientifically examine medical and health topics of interest to the public. This includes reviewing newly published studies, examining dubious products and claims, providing much needed scientific balance to the often credulous health reporting, and exploring issues related to the regulation of scientific quality in medicine.
A Blog Around The Clock 