Via Terrence Tao, here is a wiki to a substantial number of academic blogs organized by subject, and by University. No entries for Caltech!
I’ve examined the astronomy, math, and the physics entries – there are lot of blogs I haven’t visited, so it’s a pretty good source for finding new blogs on those topics. There were very few blogs listed in Engineering, numerous blogs in Computer Science and Law.
If this sounds interesting, check it out.