Excellent video lecture series on Six Sigma by Dr. Tapan Bagchi, Professor, VGSOM, IIT Kharagpur. Listening to the videos and learning about the subject will take time, but it is worthy. To listen to the series, watch here:
http://www.youtube.com/watch?v=SMOQV2CyVQo&list=PL8F39D0611CB7BD3B