IMPORTANT NOTE: As of Firefox 22, this functionality will be built in! Once you upgrade to Firefox 22 or later, this extension will therefore be disabled automatically, and you can feel free to uninstall it.
With Dock Progress, you can monitor your download progress in Firefox's dock icon. Even if Firefox is in the background or hidden, as long as you can see the dock icon you can see how your downloads are coming along.
Two distinct styles are available: "Progress bar" style shows a tiny blue Cocoa-like progress bar, while "Icon fill" style dims the Firefox icon, filling it back up with color as your download competes.
This extension works only on Mac OS X 10.4 or later.