I’ve had my Google Glass for about ten days now, and I’m surprised to see a lack of hardware hacks for it! A user on the Glass-Explorers.com forum suggested a headlight, and I agree. Presenting the Google Glass headlight dongle!
To see it in action, check out this first-person demo video!
The body is an Adafruit USB Shell (pinout here). Just connect pin 4 (ID/Sense) to pin 5 (GND), connect the anode of a high-efficiency LED to pin 1 (VCC), the cathode to an appropriate resistor, and the other end of the resistor to GND.
I used a high-efficiency cool white LED with a forward voltage of 3.8V and Imax 15mA, so I used a 33Ω resistor.
How does it work? Connecting Sense to GND puts Google Glass into USB Host mode (yes, Glass does support USB OTG!) which causes the VCC line to output 5V instead of taking it. This powers the LED! No, there’s no way to turn it off yet, but this isn’t bad for a fifteen-minute proof of concept.
Got a Glass and interested in getting your own headlight? Let me know in a comment! If there’s enough interest, I’ll build it into a simple product.
Schematics and instructions soon!
Zack Freedman 
Hi
I’m trying to use USB OTG to send data but Glass seems have an empty whitelist. Did you get any luck on that?
It looks like the
android.hardware.usb.hostpermission isn’t enabled in Glass. If you root, you can enable this and use the Android API to manipulate devices.Yep, this is rad. Keep us posted on the schematics, sounds like a fun/simple little hardware hack!