Here is yet another score given out for free by the USC Music Library: Ingolf Dahl's copy of Stravinsky's Piano Concerto.

The USC Music Library has a rack of free stuff, which is usually filled with viola parts to obscure string quartets. Sometimes you can find noteworthy items, though. I've gotten scores to Copland 3, Symphonie Fantastique, some Schubert symphonies, Carnival of the Animals, and others. Notably, I found this score of Berio's "Circles" owned formerly by Ingolf Dahl, himself.