Every web page that has a FB 'like" button or other FB gizmo is automatically recording that you visited that page in FB's data bank. That could solve some of the mysteries of why FB recommends certain friends who haven't even filled out their FB profiles -- you both probably visited the same unusual web pages, and have a few other things in common like location (FB could get it from your IP address if not from your profile). FB can do this whether or not you have a FB account and have agreed to FB's privacy policy. Considering the FB javascript code is embedded into other web pages, I'm not sure that they cannot see the data you enter into all the forms as well. What a goldmine of information that would be!!! You could clean out your FB cookies after every web site you visit, so you look like a new person to keep FB from correlating all the pages you visit and form data you fill out (assuming they don't correlate by your IP address alone). Better, you can get a plug-in that blocks anything from FB from loading into other web site's pages until you give it permission (e.g. Request Policy for FF) Or you can just accept that FB knows just about everything you do on the web, since just about every significant web site promotes itself by having an associated FB page they want you to "like". (As a webmaster, I've decided to take the lead from some German web sites, and disable the FB "like" button in my website until a person clicks on a button to enable it. And it's permanently disabled on any page where the user can enter personal information.)

There is also the RequestPolicy plug-in for FF. It can block all requests from web domain A to domain B, whether Iframe, image, or redirection. You get to choose which web site can link to which, or allow/disallow a web site to be linked from anywhere, or to anywhere. However, it is constantly blocking new web sites until you give permission, which is somewhat a nuisance, because many websites load their content from multiple domains. But the alternative is to allow yourself to be tracked all the time, so I think it's worth it, at least for me.

So why even upgrade to FF "5".0? Actually I regret even upgrading to 4.0 -- it broke one financial web site I have to use. For that matter, why bother with FF at all? With Chrome available, FF almost seems redundant. Furthermore, it seems like each version gets worse and worse with regard to the bloated amount of memory it wastes. Maybe that is due to the add-ins I use, but it is frustrating to watch my computer screech to nearly a halt when FF is "running". I keep hoping each "new, faster FF" will actually be faster, but instead it just uses even more memory and goes even slower. I don't care what part of it is faster if it takes 5 minutes to load. The only reason I haven't completely switched to Chrome is purely inertia in getting my favorite add-ins (if they exist) installed in Chrome. But whenever I have a problem with FF, I run to Chrome in an instant, and it always works. After writing this comment, I've almost convinced myself I should take the time to get my Chrome customized so I can use it full-time instead of FF, even if some of my fav add-ins are missing there.