If you've never been targeted by an ad because of your online behavior, then you're probably just not paying much attention.

According to an informal survey by the Interactive Advertising Bureau (IAB), more than 80 percent of advertising campaigns in 2009 involved tracking of some sort. The advertising business, in short, loves online tracking just about as much as privacy advocates hate it.

Privacy advocates argue that online tracking undermines citizen rights and feels a little too big-brotherish for comfort. Their concerns were part of what led the FTC to release a report last February urging advertisers to evaluate their policies and beef up their privacy efforts. The industry's response has been to improve self-regulation -- largely by adding opt-out buttons to online behavioral advertising.

Meanwhile, the rest of us are left wondering what the big deal is. We might be slightly creeped out when a particular ad follows us around the internet, but is that really a debate worth getting worked up about?

We spoke with experts on both sides to find out the very worst that could happen is if online tracking goes unchecked, or if regulations to control it are instated...