At home we used to have a thermometer that would consist of a strip of temperature-sensitive plastic that you would hold against your forehead. Inaccurate as hell, but the idea was cool enough. Now this concept has made its way to the roads (hopefully in a little more reliable version). A new temperature-sensitive road paint turns pink if the temperature drops, and can thus warn drivers about dangerous conditions.
According to infosthetics:

the varnish is made of a polymer containing a thermochromic pigment. the same type of coating is already used to make bath thermometers & frozen food packaging that responds to temperature change. however, it is the first time such a coating has been used to monitor road temperatures.

Full article: newscientist.com.