Font developer Andy Clymer at H&FJ has created a tool that modifies type characteristics in real time based on facial expressions:

From their blog,

I’m intrigued by the potential to control local and global qualities of a typeface at the same time: fingers and mouse to design the details, faces and cameras to determine their position in a whole realm of design possibilities. I wonder about the possibilities of a facial feedback loop, in which one’s expression of wonder and delight could instantly undo a moment of evanescent beauty.

[Via]