Today's ever-expanding cache of online data is a store in more ways than one. Every tweet tweeted, badge unlocked, website searched and "Like" button clicked adds to the growing inventory of user information. Data miners then sort it, package it, market it -- and companies use it to better target customers. But how much sharing is too much, especially when consumers are not given a say over how their data is used? And is the exploding availability of information actually making companies less adept at predicting consumer behavior? ... "