I can think of something that would be kinda cool (depending on how transparent the material is when it's "off").
Think about it...
You'd be able to change the color of your window tint on the fly. Want black tint today? OK. Want it red tomorrow? Sure, why not!
It's an overcast day and you don't need the windows so dark? Sure, no problem! A computer senses the amount of direct sunlight hitting the car and compensates.
Wire it up to your car alarm, and when it goes off, the windows flash along with the alarm.
Want to tell the prick behind you off.. literally? Scroll a message across your rear window. Or.. ask the hottie in the car next to you for her number in a really unusual way. Of course, these last two are illegal in all 50 states (and probably every other country out there too, since it's considered a distraction).
Realistically, it'd probably never work as a tinting material since it probably doesn't block light very effectively.
To that end, I've seen electronic welding goggles that use LCD technology to automatically darken the lenses of the goggles as soon as the welding torch is lit. It'd be really cool if a company adapted that to car windows.