Carpe Diem is a blog by Mark Perry, a professor of economics and finance at the University of Michigan-Flint Campus. He is quite active and has a good readership. Examples of recent interesting posts are one on a doctor in trouble for charging too little to treat the uninsured, another on average housing prices in Detroit (in 2004 they were almost $98K, in 2009 less than $14K), and a post showing that the number of miles driving in the U.S. has declined for 15 consecutive months.
McNamara' blog contains musings on church history by a historian. It is very well done.
The Chicago Boyz has a big bunch of contributors and sometimes they discuss interesting topics.