Doctor Who is a comparatively small category for me. I only have four sites dealing with it specifically in my feed (though, as it's significant part of geek culture, many of the sites I follow have posts about Dr. Who from time to time.)
Does Steven Moffat Still Suck? How can you not love a site with this name? From the site: "Follow for updates on if Steven Moffat still sucks. Which he does."
Not a Dead Communist: I was searching for reviews of the first Doctor Sourcebook and I came across one at this site. This site, and the reviews my friend Jen writes over at Reversing the Polarity, have done what I would have thought impossible. They've actually piqued some interest in the adventures of the First Doctor. He has a number of posts about the individual companions for each Doctor, but in the context of a role-playing game, speculating as what behind the scene pressures would have led to the creation of the Brigadier as a PC in a Doctor Who campaign. It's an entirely novel approach that I've never seen elsewhere, and it provides a unique perspective on the characters and the seasons in which they appeared.
Philip Sandifer: Writer: Probably the most intellectual analysis of Doctor Who on the net today, with trenchant, literate examination of most episodes of NuWho and every existing episode of Classic Who. Marred somewhat by his bizarre defense of Moffat's feminism, but otherwise outstanding.
Whovian Feminism: I was at a friend's party, and I started talking to her brother's girlfriend about Doctor Who blogs, as happens in all the best parties. She recommended Whovian Feminism. I checked it out when I got home, and it was just outstanding. Very cogent and absolutely relentless in defense of its thesis.