John,
The Poppy we built at Waterloo University in June for the Nengo Summer School (see this thread) was with a Raspberry Pi in the head. I hot glued it on the supports for the head_y servo with the USB sockets facing the cutout for the Ethernet at the back. I used a cutter to enlarge the hole for the Ethernet and placed 2 USB2AX in those USB sockets. The dongles stick out from the head but it’s fine - looks like someone having a deep cortical implant.