This site comprehensively lays out the Six Sigma methodology. Six Sigma sets out to define measure and analyze processes with a view to improve them and remove defects and wastage. This site gives you the history, roadmap and many of the analytical tools used in the six sigma methodology.

Although the isixsigma site has extensive information on many aspects of six sigma, I found this short article informative in terms of the six sigma and lean thinking concepts.The article references Toyota, where lean thinking became a reality in manufacturing.

Most of the six sigma examples you will see on the web will relate to manufacturing. This article, although high level, discusses such questions as “Determine which parts of your service processes are the best candidates” and “Define what you mean by a service defect and how you intend to measure it”. Altogether a good primer on using six sigma in service industries.

A booklet, 15 pages, that acts as a pocket book in terms of describing six sigma and placing the techniques ( such as control chart, data points, flow chart, histogram etc.) in their process improvement context. Pizza delivery is used as the example process for analysis.

This article from quality digest examines six sigma with a critical eye, in order to assess if this methodology offers any real value. One of the criticism it describes is that six sigma does not offer anything that can’t be found elsewhere, i.e. it is just a marketing bundling ploy. Anyway a good read, and as you go through the arguments you will certainly know more about six sigma than when you started.