Ask HN: What are some blogs of really smart people you check regularly?

What are some blogs of really smart people you check regularly?

The less mainstream or well known the better.

Edit:

I'll provide some of my own;

http://blog.asmartbear.com/archives

http://www.dilbert.com/blog/

^Mostly of entertainment value but he says some interesting things from time to time.

http://rs.io/articles