I remember visiting my friend at the Getty Museum, while he was working there over the summer, and getting a badge for the day that allowed me to see his workspace. Anyway, it was really cool, in that, by the end of the day, the badge had slowly changed color to reveal that my badge should be voided. What a fancy way of increasing security, eh?

I think heat reactive technology is really cool. Just below, is a calendar that uses a similar process except backwards.





And here are more images of reactive wallpaper: