The competitive and privacy policy implications of targeted advertising on the web pose tremendous challenges for the public interest community. Although this article doesn’t address the similar debate involving cable TV, it is an excellent and even-handed overview.

Forbes
The Looming Battle Over Targeted Ads
Legislators and consumer groups are pushing for curbs on firms that track Web users’ behavior. A primer on the coming showdown.
LOS ANGELES — No one disputes that ads are a critical part of the Web’s information ecosystem. News Web sites like this one depend on them for nearly all their revenue, as do sites like Facebook and YouTube that have changed the way we communicate online.

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Forbes – Behavioral Advertising