>Facebook's "Like" buttons track you across the internet, even if you don't have an account. There's no way to opt-out of that

There's facebook disconnect for that

Chrome plugin: https://chrome.google.com/webstore/detail/facebook-disconnec...

Firefox add-on: https://addons.mozilla.org/en-us/firefox/addon/fbdc/

(Not that I think it's reaosnable you have to install a browser plugin to opt out of this, but they do exist!)