Waltz in A-minor - Schumann, "Albumblatter", op. 124, no. 4

Download/listen here.

I find this waltz pretty crazy. From the opening, where who knows what key you're in, to the fiery b-flat stroke, to the abrupt change of mood (and key) in the middle, to the odd ending. It also has an interesting two note phrase over top of a waltz (3 beats) in the middle. I played this in a recital a few years ago, but I think it sounds much better here. If you don't know anything about Schumann, he's worth reading about on the web. An interesting character to be sure.