Does this ever happen to you? You download a DMG file to install an application, mount it, then install the app. At that point you go on your way and forget about the mounted image. Or how about you have connected an external drive or a flash drive and you can’t get to your desktop easily to eject them.
The Ejector app is a menu bar app that gives you a single place to see all the drives or disk images that have been mounted so you can eject them. This is one of my must-have apps on my Mac.