There is a generic urban-myth type story that every librarian has heard, about the patron who is looking for a book, and who knows nothing of the author or title but knows that the cover was a certain colour.
Well, in a library that used this type of classification system, no problem.
On the spine label I would suggest instead of the Dewey or LC number that we could use the Hex Colors system used for the web. So that for instance if I wanted a book in a particularly nice pink I would look under #FF 69 B4
BTW, did you know you can search Google images on a particular colour (see below) but as yet you cannot search Google books for colours, this no doubt will come.
Whatever - formerly New Technologies for Libraries Blog 
Hello Edgar I think your suggestions are great by all means lets make use of the hex colors system but in the meantime you can have a sticky at this example of a colour search in an OPAC. I remember finding this ages ago but is still amusing.
http://www.childrenslibrary.org/icdl/SimpleSearchCategory
Urban legend? I get that one about once a year, even did it myself once as a student. Trouble is the colour memory often seems to be of the book’s after-image, like blue turns out to be red. đŸ™‚
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