MacPaw today released CleanMyDrive 2, a free (with in-app purchases) utility for reclaiming free space and clean junk off of external drives and flash drives. The new app runs on OS X Yosemite and El Capitan only, and requires just a smidge of space at 12MB.
I've used the app's predecessor, CleanMyDrive, for a while, and it's a great way to make sure that you unmount drives properly -- with a click -- and that unneeded files are cleaned up when you do that. CleanMyDrive 2 has a completely redesigned user interface that follows the clean design of the last two editions of OS X, and the app is quite useful if you have a number of external drives attached to a Mac. The UI can be set up for a dark or light theme depending on your personal taste.
CleanMyDrive 2 can be set to launch at startup, and when it's running there's a tiny disk icon in the menubar. With a click you immediately see exactly what's currently mounted on your Mac, and unmounting a drive is as simple as clicking on the eject button next to the drive's name. You see the amount of storage still available on each drive as well as what kind of documents are being stored. Files that are considered junk -- like hidden service files and so on -- are automatically cleaned at each disk ejection.
One of my favorite uses for CleanMyDrive 2 during my testing of the new app was to copy files to disks simply by dragging them to the menubar, waiting for just a second for the drive icons to appear, then drop them onto the appropriate disk. That way I don't need to open a Finder window to be able to copy files, nor do I have to clutter my Mac desktop with drive icons.
Finally, if you want to do a mass unmount / eject of every drive connected to a Mac, it can be done with one click. That way you know that everything has been shut down cleanly before turning off your Mac or unplugging drives from the various ports.
In case you're wondering what in-app purchases are provided by CleanMyDrive 2, the app has a number of fun icon packs that can be purchased separately. CleanMyDrive 2 is available on the Mac App Store.