Have you seen the Idle Words talk, "Haunted by Data"? http://idlewords.com/talks/haunted_by_data.htm

Pretty compelling talk, culminating in:

    I believe there should be a law that limits behavioral data
    collection to 90 days, not because I want to ruin Christmas
    for your children, but because I think it will give us all
    better data while clawing back some semblance of privacy.