Roger Hoerl, leader of the Applied Statistics Lab at GE Global Research, is one of the leading lights in the Six Sigma movement - in my opinion. He has also co-authored several excellent books:
- Six Sigma Beyond the Factory Floor: Deployment Strategies for Financial Services, Health Care, and the Rest of the Real Economy by Ron D. Snee and Roger W. Hoerl, 2004. Highly Recommended.
- Statistical Thinking : Improving Business Performance by Roger Hoerl and Ronald D. Snee, 2001. A great book on how to apply statistical thinking to improve business results. More details on Statistical Thinking.