I'm thinking about recordings that did something novel, unusual, outlandish (etc.), but transcended their novelty and had real musical value. In other words, not the typical novelty or "party" record, that you play for a laugh once or twice and then forget about.
I'm thinking about recordings like the following:
Glenn Gould, Consort of Musicke - playing Elizabethan virginal music on a completely wrong instrument (grand piano) and making it sound right
E. Power Biggs plays Joplin on pedal harpsichord - similar to the above, except going back in time with the instrument rather than forward
Ensemble Modern plays Conlon Nancarrow - mechanical music played successfully by humans
Any others?