Well this is a fun but unusual app. I think there is a lot you can do with it. I would personally use it to write silly messages to other people.
Blackberry App World:
Try the ultimate retro style message scroller and animation player for your BlackBerry® PlayBook™. This application features an ultra realistic looking LED dot matrix screen capable of displaying scrolling messages and animations in 16 vibrantcolors. Show messages in mirrored format for people to read in their rear view mirror. Play built in animations or your own creations. The best of all: Screamager is only 99 cents! Try it now!
Download the app from here.