FireFox can block annoying popup Flash ads

FireFox is has it built-in to block annoying Flash pop-up ads, but it is turned off by default because of concerns of legitimate uses.
To turn it off:

To block pop-ups from plugins, open your Firefox 1.0 or 1.0.1 browser, type about:config in the address field. Right-click in the resulting config page somewhere and select New -> Interger.
Type privacy.popups.disable_from_plugins in the resulting dialog, hit OK, type 2 in the next dialog and you’re all set.
This pref can actually take three values:

  • 0: open allowed
  • 1: the opened windows are treated as popups, but they’re allowed to open (we limit the number of these types of popups)
  • 2: the window is a popup, block it

  • Via ForeverGeek