I remember a recent thread suggesting works by composer Iiro Rantala. Researching him I came across this piece:

Concerto for Piano and Concerto in G♯ΔA♭ (pronounced Gis-Maj-As according to Wikipedia.)



I think he is considered more of a jazz pianist however.

I also just got through watching a DVD of Peter Schickele's "Unbegun Symphony" (it has only a third and fourth movement) which is quite a hoot.