If you have a clamshell iBook (or a few iBooks) take a look at the bottom between the Apple logo and the battery. See those holes? Those are actually charging points for some sort of rack charger. Does anyone know if one of these charging stations was actually ever produced? Apparently Apple never made one, but perhaps some 3rd party did for schools or something.

http://support.apple.com/kb/TA25909?viewlocale=en_US