In some cases oddball keys were put on the PC keyboard (or to be more precise, included in the ASCII character set, most of which found its way onto the PC keyboard) because the developers figured theyd come in handy for something, and on the whole they have--programmers and developers have been able find a use for nearly every key on the keyboard, even if that use isnt obvious to the general computing public. Witness the tilde <~>, which, whatever use it may have as a diacritical mark in some languages, now can mean "home directory" or "text omitted," among other things.
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