Hmm - this does seem useful, and it is very well laid out. Something I noticed in the article under "How to":
2.solder resistor: don't cut rheophores, but use them to create the circuit;
"rheophores"? I assume something got lost in translation; I think you meant "the leads", as in "2.solder resistor: don't cut the leads, but use them to create the circuit;".
Other than than that minor bug (as well as maybe a "warning" letting users know not to press more than one button at a time, which could lead to unknown values), I think it is a pretty good writeup, and something that I could see being manufactured for Arduino and general uC usage (such as by Phidgets - maybe you should contact them?).
