Many people I know are resistent to make the switch to digital books because they want to hold, feel, and smell the material that they are reading. Part of that reasoning has now been thrown out the window thanks to Paper Passion.
Originally produced for use at a magazine exhibit in Milan, Paper Passion is a bottled form of the smell from inked paper. It apparently is meant for human use (why anyone would want to smell like paper is beyond me though), but a small squirt on that e-reader and you are transported back to when each page needed to be turned in order to read. To capture that nostalgic experience will set you back $115 though.