I'm one of these people that dislikes trailing wires over my desk and gets fed up with continually replacing batteries for a wireless keyboard and mouse.
I came across this Logitech Wireless Solar K750 keyboard today and although a tad expensive at £70 ($105) I took the plunge and bought it. Logitech UK - Wireless Solar Keyboard K750
It has a row of solar panels above the keypad, which is very similar in design to an Apple Mac keyboard.
It has a Solar App you can download that lets you know the power state of the solar panels (which get a charge off roomlight as well as daylight) and another download that synchronises the keyboard with a Logitech wireless mouse, which means you can control both with just one USB wireless receiver.
It also comes with a three-year manufacturer's guarantee.
I have no connection with Logitech whatsoever, but just wanted to let you know about what I consider to be a seriously good keyboard.