I had a problem with my ibook – the areas next to the trackpad (in front of the keyboard) had gotten grubby one sunday with newsprint on my hands from the NYT and I couldn’t get it out for the life of me. So I was at the library trying to study, and found that a white eraser cleaned up the click wheel on my ipod mini pretty well, and that’s the same porous plastic as that part of the ibook, so when I got home I put my trusty Staedtler Mars Plastic Eraser to work, and the grubbiness is gone! Looking at the Staedtler site, they even recommend their plastic eraser for cleaning wallpaper and lightswitches.