The Beethoven Fantasia Sonata 1792 on your handy? Martin Oei made two ringtones:
The ringtones are both excerpts from the 3rd part of the Fantasy Sonata.
The slow ringtone starts from bar 660 (the moment when the 2nd theme begins, a wonderful theme in a-flat major, the key of love, a moment of beauty in any case), and ends at measure 733.
The other ringtone begins at bar 885 and ends at measure 927. It begins pianissimo and then there is build-up to fortissimo with heavy accents and it contains very exciting moments.