Today when I was at my piano workground I encountered horn player and was forced (but eventualy it turned to be pleasure and great experience) to listen to his playing (very clearly despite two closed doors and hallway between us). Then I had conversation with other guy about french horn music and I've realised something:
French horn, at least in my opinion, has pretty weak repertoire. It's magnificent instrument with noble and rich sound but there are very little pieces for it that are real masterpieces of the same caliber as greatest violin or piano concertos.
But horns often get their "five minutes" in non-concertante orchestral music. Tchaikovsky's 5th, Mahler 5th, some Richard Strauss, Wagner (Siegfried's signal and many other short pearls).
Can you think of some other examples?