itwbennett writes "Do you know what data the 1300+ tracking companies have on you? Privacy blogger Dan Tynan didn't until he had had enough of being stalked by grandpa-friendly Jitterbug phone ads. Tracking company BlueKai and its partners had compiled 471 separate pieces of data on him. Some surprisingly accurate, some not (hence the Jitterbug ad). But what's worse is that opting out of tracking is surprisingly hard. On the Network Advertising Initiative Opt Out Page you can ask the 98 member companies listed there to stop tracking you and on Evidon's Global Opt Out page you can give some 200 more the boot — but that's only about 300 companies out of 1300. And even if they all comply with your opt-out request, it doesn't mean that they'll stop collecting data on you, only that they'll stop serving you targeted ads."