I've been talking about this in the Arduino irc room for a few days and thinking about various aspects of it, and I've finally put together a page about what I've named "The Unduino Challenge".
It's a not-so-serious Arduino based challenge aimed at everyone from total beginners to half-cyborgs, in which a simple objective is set - but the obvious solutions are not the most desired.
Although it might seem counter-productive to design these machines I think they are great for beginners to better understand what and why some things / methods are bad practices.
I dont know about counter-productive. Inefficient, almost certainly - but not counter-productive! Think of all the stuff you will learn!
I've had a couple of ideas for tasks. The initial one that I came up with (which won't be used, so I will tell you as an example) is:
Turn on a light when a button is pressed.
The obvious solution is to use a pushbutton and LED straight into the Arduino. There are an infinite number of other solutions, though (turning on your porch light when a key on your piano is pressed, for example). Those are the solutions that this challenge is looking for!
For example, there was an instructable on getting a (real, hardware) button to work with a PC running MaxMSP/Puredata: The idea was that you set it up to output an audio tone on one of the earphone channels, put the button in between the audio out and audio-in, and then use an "audio meter object" with a threshold to trigger an event when the button actually connected the tone to the input.
