My favorite way to find quality blogs (and books and movies, for that matter) is via recommendation. Towards that end, I thought I'd share a PPC Blog you might not be reading (every so often we share a list of our favorite search and online marketing blogs ).
Aaron and Giovanna Wall of SEO Book fame have started collaborating on a sister site that focuses on PPC. The content is really strong, offering a very similar level of high quality how-to and industry trend material. They recently launched a very clever AdWords tax calculator that can help give you an indication of how much you might be wasting on paid search.
If you haven't already it's definitely worth checking out and subscribing .