It's a fun if macabre project.
I kept the right rear dropout and most of the downtube. The right rear dropout just seemed like the point where I had poured years and years and miles and miles of energy through. It also has a pleasant heft, and after some time with a grinder and a file, nice smooth edges.
The downtube has the brand name and looks good hanging on the wall near my desk.
I tried making a flute out of the top tube, but I learned that there's a lot more to making a flute than drilling some holes. It does make some nice tones, but they don't relate to each other in any way.