Just a snippet today, as much to remember it as anything else:
If you're using VirtualBox on Linux and USB devices aren't working despite the fact you've installed the extension pack, it's because you haven't remembered to add yourself to the vboxusers group.
To do that:
# usermod -a -G vboxusers your-user-name
...and then you'll probably want to log out and log back in so your UI processes pick up the change.
