The blog Patently-O is a worthwhile site to visit periodically. That is if you’re interested in the arcane cosm of patents like I am. The fellow who writes the blog is Dennis Crouch, Asst Prof. at the University of Missouri School of Law. The post on USPTO guidelines on obviousness is particularly interesting. I find this to be the most vexing part of patent law.
Anything Under the Sun, by Russ Krajek, is another useful site to visit if you want to glean useful tidbits on patent practice. These sites are maintained by people interested in their field and are happy to share insights with others.