With computers getting smaller and smaller and more and more efficient, its only a matter of time before they get small enough inside a USB key and get powered with USB juice.
There are USB key computers already, but what I really want is a USB powered firewall dongle. I recently blogged about wanting a pfSense powered USB firewall, but honestly anyone will do.
The question is how it will work - it would be preferable to have two ethernet cables and one wireless interface. The problem is that these items take up room and energy. One idea is to use USB for networking too, but I haven't found that to be too common with linux systems.