Pop-Up Stopper Free Edition from Panicware.
The free Pop-Up Stopper prevents annoying ads (and pop-under windows) from displaying. You can have sounds notify you when a pop-up has been blocked. The program also allows you to briefly disable the blocking by double-clicking the system tray icon or by pressing Shift or Ctrl when following a new link.
Supports Internet Explorer, Netscape & Mozilla only.
Microsoft Windows 98, 98SE, ME, 2000 or XP.