Found a treasury of beautiful Cello music - would be good to try on Viola, too! 

Adam Hurst Biography

From last.fm:

Adam Hurst has an original and unique improvised melodic style of cello playing. His music blends Middle Eastern, Indian, and Gypsy traditions with Western Classical in haunting, and seamlessly flowing compositions. He has been described as "mesmerizing", "spiritually inspiring", and "a hypnotic cello player". Live and on his recordings, he performs alone.

"Fragmented" - "Filmmaker Jason Okamoto's experimental vision of the creative process of Adam Hurst." 

Adam has great current work, but I also really love some of his earlier pieces.  Sometimes he adds his piano, kalimba, oud, or like in this video - Spanish guitar!

"Night Dance" - Cello & Spanish Guitar by Adam Hurst.