One thing I like about the google bar is that it tells you when it's blocking a pop-up and also that your can on a per-site-visit basis re-enable them which is useful for the occasional site that uses popups legitimately.
Definitly handy, and this is one reason I switched from Mozilla to Firebird a while back.

I'm going to have to look into the Google AdWord killer for Firebird. It's amazing what people are doing with the extensions.