The decoration of them is awesome regardless of the subject matter. These "musical" cookies from Cookie Craze have a casual look about them and those iced treble clefs have been piped with a lot of confidence.
From The Art of the Cookie comes these striking orange on blue musical notes.
and these round cookies:
And here's a solution from Con-fec-tions for musical notes: if you don't have musical cutters, use another shape such as a heart shape or (as above) a square shaped cutter...
When I get time I'm going to do some of these for the lads.