This design is called Natural Notes Business Cards.
This design is called Pocket Piano, which folds into a mini-piano.
These are very unique, called Songs in the key of nature.
These are a little more old school, called Hit the Right Note
This design is called Funky Piano:
Wedding pianists may want to consider the Wedding Fever or The Big Day collection - its meant for wedding planners, but the design can easily be altered for a pianists' purposes:
These aren't really related to music, but I also like the Making Change collection, which are based on quotes of Seth Godin:
Another design is Classical Composition: