I believe I have a book similar to the one Foolestroupe described in the first post--however, I think it covers only themes from classical music, not popular tunes.

It has practically no usefulness to me, yet I found the concept so fascinating that I bought it anyway when I found it at a used book sale.

If you know a tune that you want to look up, you first transpose it into the key of C, and then write it down as a sequence of notes, for example, CCAGB etc., ignoring the duration of the notes. Then you look it up in the index where all the tunes are listed alphabetically according to their note pattern. The index then refers you to a page where the tune is written out in standard notation (not the whole tune--usually just one or two lines of it) along with identifying information.

Great concept, no? I see no reason why the same thing couldn't be done for popular or folk tunes.

I don't remember the name of the book and I won't be able to look it up for a few days. If you're interested, please PM me to remind me to look it up.