I think the worst effect of all would be the complete individual profiling that could be then done. My taste in sci-fi novels is no one's business. Then again, it looks like most cultural goods are going digital and their purchase will then be traceable anyway. I can see a need for proxy purchasing agents emerging at some point.
For each man, according to the measure of his intelligence, must speak what he can speak, and do what he can do. - Alfred, King of Wessex
Calm down, have some dip. -George Carlin