Quickfire is a recently released experimental Firefox add-on that lets you find and launch Mac applications straight from Firefox's
address awesome bar. Just like in Quicksilver, Spotlight, and any other launch helper, you need only to type a couple of letters to get it going. It doesn't provide icons for each application, but it will show you the root folder where it's stored, and loads up the app as soon as you hit enter.
If you're on a Mac there honestly isn't much use for this, since the built-in Spotlight can do the same thing with a very simple and easy shortcut of its own. However it can, occasionally, come in handy if you're in the middle of using some Web app and realize you want to fire up a certain outside application, since the result suggestions load up the same way they do for site history and bookmarks.