Simple: a solar panel, 2.5W, output 5V and 500 mA, with a USB jack attached. In sun, you plug your USB device (ipod, phone etc) into the solar-powered USB jack, and it charges.
Pure, simple. Who’s got it?
http://www.rei.com/product/770230 – $115 == $40 a watt, that’s Not Right.
http://www.modernoutpost.com/gear/details/sf_solar_uno_slim.php – another candidate, fifty dollars, much closer… but still, $20 a watt… that’s Not Right either.