I just got my Leaf a few days ago and when comparing cars I couldnt believe they wanted $350 for a light in the grill emblem. I think this weekend I am going to have a look at the clear plate and see if there isnt a way to add LEDs to it. I have a background and am not shy around things like soldering and circuit design.
I think the best method of lighting it up would be to attach LEDs around the outer edge (not from behind). But until I remove the grill and look at it I wont know how much space there is, or how accessible that edge is. The next step would be to play with brightness and color. Here in CA they tend to get irritated if you have visible blue lights on the front of your car, so that may be an issue since the plastic is blue. I still have blue and red LEDs from when I replaced all the green ones in my IS350 (gauges, radio, hvac, window switches, etc.). But these are mostly surface mount and I may have to get some standard legged ones to play with. It would be cool to maybe have a switch where you can change the color scheme with blue as the primary base, for example white LEDs would make it glow blue, red LEDs would make it glow purple, yellow LEDs would make it green.
I will come back and post some pics and my findings when I get the time to actually do it.