[djcapelis]

http://taco.dubfire.net/ and http://www.networkadvertising.org/managing/opt_out.asp are of some use for this.

Also if you're using whitelists, they will only track you on the sites that you're choosing to whitelist, so it's not as if whitelisting Ars will immediately allow them to track all your moments.

Neither of these are perfect solutions to your concerns, but I thought they should at least be mentioned.