do you have Firefox set to block popups? in tools > options > content > check box "block pop up windows"

I don't use it but there is Adblock Plus:
https://addons.mozilla.org/en-US/firefox/addon/1865
Maybe I should, it looks good.

Flashgot is a good one for assigning things to be downloaded by GetRight (resumable downloads).

I also use the Super Mario Bros. 3 extension.