I delete my really old tweets, but it was actually to make the Advantage Bluetooth-enabled!

I added a Bluetooth keyboard converter, LiPo, and charge controller inside the case.

Unfortunately the Sparkfun documentation for the charge controller implied that it would prevent undervolting which wasn't true, and the battery died. They fixed the documentation but wouldn't send me a replacement battery. I didn't have the money for a new one at the time and reverted it.