Stampendous have a couple, one is a music score background size, and one is a collage with music and instruments.
On the cute side, Penny Black have some lovely ones - flute, guitar etc. If I knew I'd use them more than once I've been SO tempted by both those. And I do have their one of 3 mice on a piano, get a lot of use from that one.
You can nice little music eyelets too -
www.eyeletoutlet.com have the quickset ones, not sure where I got the regular ones that you need a setter for. Perhaps Buttons Galore?