Homer Simpson can finally resolve his keyboard dilemma with this open-source Any Key. It can, as the name suggests, perform "Any" keystroke.
The Any Key is a simple one-button USB HID keyboard that can be programmed via a virtual keyboard to replicate any keystroke (or combination of keystrokes) required for simple operation. The entire device schematics and software are open source and readily available, and while it is somewhat on the silly side, there could be some applications for single button input devices of this type.
Mind you, I'm still trying to find the PigUp key after many years of searching.
Finally, Someone has found The Any Key [Hack A Day]