Horn Concertos

If by horn you mean the commonly understood usage in orchestral music circles--that is, the french horn--then yes, sadly, they do not get played very often. Mozart wrote four horn concertos, and Haydn at least two (perhaps more, i only know of two).

If you mean "brass" in general, then i would point out that one of the best recordings of Haydn's trumpet concerto (the best in my opinion) is the Wynton Marsalis performance.

My brother plays french horn, trumpet, cornet and piano. I've heard the horn concerti of Mozart and Haydn since i was a very small boy. Haydn's second horn concerto's adagio is one of the most hauntingly beautiful passages in his composition . . .