We have pieces in the following keys for Viola:
1-20 of 405 Viola Pieces in D major

Mussorgsky
Pictures at an Exhibition No.3 - Tuleries

Bach
Musette

Chopin
Nocturne Op.32 No.1
(subscription)

Scott Joplin
Maple Leaf Rag

Satie
3 Gymnopedies no.1

Borodin
Polovtsian Dance

Vivaldi
Spring from The Four Seasons

Bach
Air on the G string

Trad.
Silent Night

Severac
In the park

Mendelssohn
Hark the Herald Angels Sing

Michel Corrette
Fanfare

Ponchielli
Dance of the Hours from La Gioconda

Trad.
Star Spangled Banner

Handel
I Know That My Redeemer Liveth from Messiah

Trad.
When the saints go marching in

Flotow
Aria from Martha

Chopin
A Wish

Schumann
Humming Song Op 68 No 3 (from Album for the Y...

David Bruce
Freshtown Rag