-FastML http://fastml.com/
-MLWave http://mlwave.com/
These first two are great for Kagglers as they often go through competition entries.
-Chris Olah's blog is quite new but has been excellent in explaining concepts http://colah.github.io/
-Mike Bostock's (creator of D3.js) blog has some brilliant visualisations. http://bost.ocks.org/mike/
