Entirely too many to choose from, but just to name a few:
Mozart: Concerto K.467, second movement (even if it's been nearly done to death)
Beethoven: 'Emperor' concerto, second movement; Op.109, first movement
Chopin: Concerto No.1, second movement; Etude, Op.10 No.3; Nocturne, Op.15 No.1 and Op.48 No.1; Berceuse; Barcarolle
Liszt: Transcendental Etude No.3, 'Paysage'
Brahms: Concerto No.2, third movement, and also the re-appearance about five minutes into the first movement of the orchestral entrance from the introduction
Grieg: Concerto in A minor, second movement and F major interlude in finale
Lyapunov: Transcendental Etude No.5, 'Nuit d'ete'
Debussy: 'Jimbo's Lullaby' from Children's Corner; 'Reflets dans l'eau' from Images I; 'Et la lune descend sur la temple qui fut' from Images II; Reverie; Ballade in F major
Faure: Barcarolle No.6, Op.70
Rachmaninov: Sonata No.2, second movement
Bartok: Concerto No.3, second movement
Shostakovich: Concerto No.2, second movement; Preludes Op.34, No.22 and No.23; Op.87, preludes in D major, F minor, C minor, F major, fugues in B-flat minor, F minor.
Not for piano: again, too many to choose, but the slow movement of the Shostakovich Cello Concerto No.1 ranks high on the list, as does the finale of the Mahler Symphony No.4 and the Adagietto from Symphony No.5, and the slow movement of the Rachmaninov Symphony No.2, and the slow movement of the Elgar violin concerto, and on and on and on....