A very nice slidedeck from Jeff Hammerbacher of Cloudera. It goes over k-means clustering and some enhancements.
Jeff Hammerbacher, founder and Chief Scientist of Cloudera, gives a nice talk about data science. He explains what he has done in the past, and what he plans to do in the future.
It is the second video, I have posted recently, emphasizing the importance of data science for more than just advertising. Jeff is getting involved in a Medical School to see how data can help.
Note: The video is about 45 minutes, but it contains some really good information.