Harder the me just listing them, but you can take a look through my Google Reader shared items:

http://www.google.com/reader/shared/10530692481246922106

The most frequent ones are:

* Schneier on Security ( http://www.schneier.com/blog/ )

* Statistical Modeling, Causal Inference, and Social Science ( http://www.stat.columbia.edu/~gelman/blog/ )

I also follow a bunch of significant python people and the artima weblogs.