Disk Master is an application that is all about internal and external disks.
Eject the volume with a single click. You can also eject all volumes at once.
You can choose to either show a small popover window or a more feature rich window.
Receive a notification once a disk is connected or ejected.
The app shows the current usage of the disk in a graph.
Monitor the statistics of your connected disks.
If a disk is shown in the menu bar, you can assign a quick action to it. You can easily eject the volume or open the Finder at a specified location.
The app lists all of your disks in a lightweight window. You can also display each disk in the menu bar as a separate menu bar item (you can choose from a wide variety of views).
Click on the screenshot to enlarge it. To see additional screenshots, open the App Store page.