An interesting prototype: a colored Apple Pro Keyboard. This keyboard model, shipped with iMacs and Power Macs around 2000, is an improvement over the previous model. It reintegrates the function keys between the numeric keypad and the standard keys, and removes the power button from the keyboard. The final version only exists in a transparent iteration, but Apple had evidently considered offering colored variations (perhaps for the iMacs?).
The keyboard uses a Japanese layout, and there is a dedicated thread about it on the MacRumors forum. It’s a green model, possibly intended for an iMac of that era.
Mac OS X
Power Mac G3