Free Sheet Music for Horn at IMSLP.
I wanted to make sure that everyone has this link, I am surprised at the number of people still unaware of the International Music Score Library Project (IMSLP).
This is a completely free collection of sheet music in the public domain for your printing and playing pleasure. Since many of the scores and parts are scanned in by users, check to make sure the pieces are readable before printing, I've run into this just a few times. If you want to skip ahead to the horn music, here is the link to bookmark.
Make sure to grab the Kopprasch high horn etudes (op.5) while you're there, they can be difficult to find otherwise.
February 6, 2009