The topic isn’t “Favourite Lesser Known Programs that run on Arch” but “Favourite Lesser Known Programs”, so 
[Edit: It’s how I get EOS onto hardware.]
For those with rooted Android phones - try out DriveDroid.
Copy an ISO to your phone as is, connect the phone to your pc, fire up drivedroid and you’ll be able to boot from your phone. You can hold as much iso’s as your storage space allows.
I haven’t needed to write an image to an actual usb device for years. 
From its website:
DriveDroid simulates a USB thumbdrive or CD-drive by using the Mass Storage capabilities in the Android/Linux kernel. ISO/IMG files that are stored on the phone can be exposed to a PC like any other USB thumbdrive capabilities. That includes allows booting from the drive as well. The combination makes it quick and easy to do OS installations, rescues or have a portable OS on the go.