Martin Howse just posted his documentation of a simple HID sensor board, costing approx EUR 5 to make, which can be used over USB with PD, SuperCollider, etc.
This board was used during a sensor workshop which took place at Pickled Feet in Berlin on 15 March 2008, with the second part taking place on 26 April 2008. Details here:
http://1010.co.uk/workshop.html
Further docs could include step-by-step programming instructions, sensor connection schematics and sample PD patches.
Feedback more than welcome!
best, d.