The Incipio company recently launched a new line of iPhone 4/4S cases that have been treated with a thermochromic layer and change color when held in the hand. Basically, that layer with which the case is treated reacts to the heat emanating from the hand and changes its color after a fairly short period of time, the case will look like you see in the pictures in this article. Of course, this case is not the only one of its kind and the worst part is that Incipio only produces it in a pink version for the price of $35.
If you are interested in other cases of the same type, then you have two alternatives, one being the case Tuffwrap Shift presented above and available for $30 plus the foil from RF Laserworks which is available for only $12. The worst part is that this kind of cases might not work as well as you imagine.
