We have pieces in the following keys for Piano:
1-20 of 599 Piano Pieces in C major

Scott Joplin
The Entertainer

Beethoven
Ode to Joy (9th Symphony)

Vivaldi
'Spring' from the Four Seasons

Chopin
Nocturne Op9, No2

David Bruce
Jingle Bells Boogie

Trad.
Twinkle Twinkle Little Star

Trad.
The Star Spangled Banner

Trad.
Away in a Manger

Ravel
Bolero

John Legend
All of Me

Mendelssohn
Wedding March

Handel
Water Music

Trad.
La Cucaracha (Mexico)

Brahms
Waltz

Tchaikovsky
Dance of the Flowers from the Nutcracker

Vivaldi
Winter from the Four Seasons 2nd movement

Dvorak
Largo from the New World Symphony

Pachelbel
Canon in D

Offenbach
Can Can

Tchaikovsky
1812 Overture