If I could make everyone read one blog, it'd easily be Greg Mankiw's eponymous blog.
We used Mankiw's text in my micro-econ class during my first semester of undergrad. My professor (not at Rice; I transferred) was a Democrat who told us several times that Mankiw was also a Democrat. So I was quite surprised when Mankiw accepted a position in the Bush administration. Either way, he's quite bright, and writes clearly. He's back teaching econ at Harvard now.
UPDATE: I didn't intend to post this until I had finished writing it. I had set the post to a future date, and forgotten to finish writing it. Oh well, I guess.
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