Dimensional Fund Advisors (http://en.wikipedia.org/wiki/Dimensional_Fund_Advisors http://en.wikipedia.org/wiki/Dimensional_Fund_Advisors) diversify among curren

Dimensional Fund Advisors (http://en.wikipedia.org/wiki/Dimensional_Fund_Advisors http://en.wikipedia.org/wiki/Dimensional_Fund_Advisors) diversify among currencies, markets, and asset classes according to some math I don't really understand. They seem pretty sharp, though, and they're low-load for the buy-and-hold version (they have market timing funds designed to lower the fluctuation at the cost of lowering the long-term return).