I've had my USB socket from Burnsmoto for a couple of months now so I wanted to put up a mini-review.
First off Burnsmoto was great to deal with and gave a free shipping discount for ADVrider's. It arrived in 2 days.
I've ridden with mine both closed and with the USB plugged in in the rain without any problems. It charges my Galaxy Nexus as fast as a wall charger and faster than my car. The socket is compact enough to stay out of the way. I wired it straight to my battery, routing the wire with the loom.
I couldn't decide where to mount mine so I ziptied it to my left bar for now. Next is a Ram Finger mount.
I am very pleased with it and recommend Burnsmoto.
Pics of it on my old DR.