My posts on Analytic bridge regarding regression,cross validation, and predictive power http://www.analyticbridge.com/profiles/blogs/cross-validation-in-r-a-do-it-yourself-and-a-black-box-approach http://www.analyticbridge.com/profiles/blogs/use-press-not-r-squared-to-judge-predictive-power-of-regression
Theo's Data Science Blog 