You know, I never really thought about this before. It's obvious that clicking the "like" button will give Facebook information about you, but what's less obvi

You know, I never really thought about this before. It's obvious that clicking the "like" button will give Facebook information about you, but what's less obvious is that just by loading the widget, Facebook gets the referrer, and can essentially track every page you visit (at least, the ones with like buttons). And the same would be true for Facebook Connect widgets. Even if you don't use it to log in, Facebook still gets your IP and the URL of the page you're on. It's a brilliant strategy. Figure out how to get your iframes on as many pages as possible, and you've got an easy way to track your users' surfing habits, second-by-second, as they navigate from one widget-loading page to another... Of course, ad companies have been doing this forever, but ad providers aren't ubiquitous, and they don't have your real name, address, etc. And everyone [edit: everyone who cares about these things] runs adblock anyway. But how many people block widgets, or would even think to?