I've thought about it many times. I even put together one myself with a 12V folding solar panel and an Energizer USB battery charger.

Instead I decided to go with learning how to better use my compass. It weighs less than any of my proper navigation gear, it's proven technology, and no batteries!

Besides...Between the extra batteries in my pack, the GPS in my phone, my old Garmin GPS12, AND the 4 compasses (1 regular, 3 button), I think I'm still in overkill land.