Hey there!

You can use a custom texture for each book placed in the bookstand.
Just use the enchanting table book layout and save it as "book*enchantment_id*.png" in this folder e.g. book1.png will give the Protection book a custom look when rendered in a bookstand. You can find a list of all enchantment ids here: http://minecraft.gamepedia.com/Enchanting#Data_values
Finally, if you choose to use this feature, you must completely reload minecraft for it to work correctly.

Thanks,
Watkins