I'm getting ready to do the LED mod myself having just received a big ol' bag of LEDs in various colors. (went with orange to better match the brass mods)
In addition to the indicator LED I'd like to add a little internal lighting inside my Ouya to see if it can be made to shine through the CAI port I installed in the case.
I'll be trying out running multiples in parallel to see if it drags the circuit down and makes them run dim.

FYI:
I measured a little over 2.8 volts at my Ouya's LED.
Using a 3V coin cell came in handy for trying out the different colors. I just held the case lid over the LED to see how each color looked.