Found this on boingboing today.
So inventors, need a super hydrophobic surface? Artists, how about a large roll of thin wood veneer? (heh I want some of this myself) Nerds, There are entire sheets of temperature sensitive material, forget mood rings, make a "mood book" or go with the polyester blend and make a mood shirt!
Presenting Inventables! Yeah, I bookmarked it.
(They have their own blog too!)