Recently on my Linux Mint 13.2 system I was playing with Virtualbox. I wanted to pass through a USB device to a virtualbox VM but despite installing the appropriate extension pack, I was greeted with this lovely message in the USB menu:

No USB devices connected

I discovered here that you need to be a member of the vboxusers group. One quick command solved this:

sudo usermod -a -G vboxusers <username>

Once I did that I logged out and logged back in. Voila! USB passthrough worked.