I have a fake book which has a song finder. For a sequence of notes, just write down whether each note is higher, lower, or the same as the preceding note. There is a table at the end listing, for all such sequences, the songs that match the sequence. Works like a champ.
I've always thought it would be nice to write an engine to crawl the entire classical ouvre looking for more examples of cockney influences, in a homage to the great Bill Bailey[0]
Looks like these people have sort of genericised that idea, but what I'm talking about is more of a fuzzy search. Shame the code isn't available along with the dataset.
From the FAQ: "scores published in the last 85 years are mostly copyrighted and therefore unavailable in our corpus" [ http://www.peachnote.com/info.html ]. The corpus comes from http://imslp.org/ , a site mostly devoted to out of copyright scores (e.g. "classical" music).
It'd be nice if it was possible to search up an exact song based on the melody. Sometimes I remember a melody but I can't remember what song it came from, and it drives me nuts trying to find it.