We are being tracked and yes they do tailor ads to what you look at. I don't worry too much about most ads though. I just ignore them.
One company called Bettersurf downloaded a program into my computer for thier ads. That's crossing a line. I consider that as unethical malware. The ads they were posting were less than ethical too. Things like "Click here to clean your computer". Usually clicking an ad like that will just make matters worse.
If you're using internet explorer you can go into your tools and change the settings on your pop up blocker to control at least most of them. Only thing is if you click on links posted here you'll have to start right clicking the links and opening them that way. It's an extra couple clicks but not a big deal.
Rodney