Bizet Variations Chromatiques if you want something that's never played, Schumann Abegg variations, although I'm not too fond of them, I just found some 'Norish Variations' by R. Stevenson on a CD from Donna Amato, and I kinda liked them, but I know nothing about them, so not how long they are and how much there are, Beethoven Variations op. 34 are around 12 minutes long, some Mozart.