I looked through the some machine learning blogs, most of which are listed here, and this is what I found:
Machine Learning Theory – Widely read
http://hunch.net/
Edwin Chen’s blog – Great Visualization, Great Posts
http://blog.echen.me/blog/archives/
Maxim Raginsky’s The Information Structuralist – Some Econ, Some AI
http://infostructuralist.wordpress.com/
Brendan O’Connor’s AI and Social Science blog – Econ, AI, great graphics, fun posts
http://brenocon.com/blog/
Matthew Hurst’s Data Mining: Text Mining, Visualization and Social Media: – Lots of post and images
http://datamining.typepad.com/data_mining/2012/07/index.html
Mikio Braun’s Marginally Interesting MACHINE LEARNING, COMPUTER SCIENCE, JAZZ, AND ALL THAT
http://blog.mikiobraun.de/
Bob Carpenter’s LingPipe Blog Natural Language Processing and Text Analytics – Full of interesting stuff
http://lingpipe-blog.com/
Computer Languages, Matlab, Software, Cool Miscalaneous
http://www.walkingrandomly.com/
Sports Predictions, Lots of other cool ML stuff
http://blog.smellthedata.com/
A personal blog with several AI related posts
http://mybiasedcoin.blogspot.com/
Personal blog with many technical post (some AI)
http://www.daniel-lemire.com/blog/
Three or fewer posts this year:
http://mark.reid.name/iem/
http://blog.smola.org/
http://yaroslavvb.blogspot.com/
http://www.inherentuncertainty.org/
http://justindomke.wordpress.com/
http://nlpers.blogspot.com/
http://www.vetta.org/
http://aicoder.blogspot.com/
http://earningmyturns.blogspot.com/
http://yyue.blogspot.com/