J.D. Steinhilber runs his own investment firm - Agile Investing (http://agileinvesting.com/) - that manages client portfolios using a pure-ETF approach, and writes a newsletter about ETF investing. His work stands out for its quantitative rigor, and we particularly appreciate his comparative analysis of asset classes. Sign up for a free trial subscription to Agile's newsletter. (http://www.agileinvesting.com/default.aspx/MenuItemID/72/MenuGroup/Home.htm)