Now, the display isn't fancily sized or anything, it's a simple straight design with each segment measuring 5 straight blocks. And it's powered (or the lamps are at least) by torches, meaning that instead of surrounding the lamps by black wool you could surround them by other lamps also. The extra lamps will never light up, and will just help the display to blend in and look nicer. Everything is timed together, so if I press my "all on" switch, every segment turns on at the same time (after a delay of about 6 ticks). I used instant repeaters where I could, so it runs fairly quickly. With this display you can show every number, letter, and most punctuation. And it also works with pistons just fine, if you put a solid wall in front of the lamps, and replace the lamps with sticky pistons. (BTW it's 31 blocks wide, 17 without the redstone)
The pictures are in the attachments.
Picture 1: The front of the display (off)
Picture 2: The wiring on the back side of the display
Picture 3: The torches directly behind the lamps
Picture 4: The area for programming the images (infinitely expandable, and fits perfectly with instant repeaters, so has 0 delay the further you go)
Picture 5: The single lines for programming images (put a torch over each line you want to be turned on)
If someone wants to download the world, you're gonna have to teach me how to put up a world download first I might be able to figure out how to give you the file using the world edit saving system though...