For an interesting art project, Instructables member jocelynzada has experimented with "Galvanic Skin Response" - in other words the amount of conductivity in our skin, which changes depending on our stress levels. By creating an Arduino-based device to measure the GSR of a user, the values are sent to a PC running processing which converts the data into a black growth on the screen.
This growth increases in size in proportion to the amount of stress, and represents the concept of disease, negativity and so on. Hopefully by using this device the operator can reduce their stress levels and create positive thoughts to help reduce stress when away from the machine.
Certainly some interesting theory, and also a good demonstration of interfacing an Arduino with processing sketches - so check out the Instructable for more information. And for more, we're on twitter and Google+, so follow us for news and product updates as well.