Qubes 3.2 has support for USB passthrough. This one feature has made Qubes so much more useful for me. It means that a wide variety of devices — from my laptop’s internal webcam, to plugging in smartphones to transfer data or do Android development — are finally supported. I used to have to use a separate non-Qubes computer for several tasks that I can now more conveniently and securely do within Qubes.
One way that I use USB passthrough on a daily basis is with my Yubikey. (If you’re unfamiliar, Yubikeys are small USB devices that can be used for two-factor authentication, for storing and typing static passwords, and for OpenPGP smart cards.) Normally when you use GnuPG, you keep your secret key in a file stored in
~/.gnupg. If you use an OpenPGP smart card, you don’t have your secret key on your computer at all — instead you have it stored on your smart card. With a smart card you can use your secret key, by decrypting or signing messages, but it’s designed to be impossible to export the secret key itself.