My Invention: Digital Bumper Sticker

I have a cool idea that I need to patent. It's a digital bumper sticker. It would be a bumper sticker on the rear of your car that you could program at any given moment. It would have some pre-programmed sayings, like:

Have a Nice Day!
Bush Sucks!
or whatever. But it would also have a modest keyboard that would allow you to type the message of your choice and have it appear on the rear of the car. It could be like those scrolling digital stock tickers, or perhaps static.

Now there would be a few concerns:

1. Obscenity. The temptation would be to write curse words. Maybe we could just block out the worst ones? Or maybe let it slide.

2. Road Rage. It's easy to see these things leading to a degradation on the roads. But wouldn't it be nice to be able to go around that guy blocking the passing lane and pop in "Move Over Jerk!"?

3. Distraction. We might cause accidents because anxious drivers were trying to type and drive. Eliza does this with her treo. It makes me nervous. I'm not sure what to do about this one?

Might need to resolve these issues before I get my patent and fire up the factory in China...

By the way, I googled my invention, and found that some others have had the same idea. It's like I'm Bell and these guys are that other inventor no one remembers.

http://www.halfbakery.com/idea/Digital_20Auto_20Banner_20(DAB)#1129390964
http://www.tonkatronix.com/mesenger/index.html