As you pointed out, Usability Post is one of my favorites, and SvN is clearly a leader.

Boxes and Arrows (http://www.boxesandarrows.com/) is also pretty rad.

I keep an eye on Subtraction (http://subtraction.com/), Khoi Vihn's mostly personal blog, too. He's the interaction designer for NYTimes, second to none...other than our own Loc Ngo, of course.