Like most people, I have to flip back and forth between Firefox and IE (Maxthon, actually). There's no easy way to do it… unless you're running Optool. A longer right-click will invoke a menu that opens the current Web page in another browser! Easy as pie. Plus, you can resize the window, go to the Parent or Root URL, and monitor the clipboard for Web addresses. Nice, even if it's not quite ready for Maxthon. This isn't a plugin, though – it's a standalone (unobtrusive) utility for Windows.