I'm a classically trained pianist who dabbles in various other instruments (saxophone and guitar being the main ones). I enjoy jamming around on the piano for extended periods of time trying to play various popular songs by ear, although few things will beat learning a technically and harmonically complex classical piece like a Rachmaninoff prelude or Liszt etude well.
Unfortunately, it's exceedingly difficult to find the time to practice a piece enough here at Caltech, so I've settled for doing chamber music every term, which is pretty fun too. I'm also a member of the Keytones, Caltech's all-male a cappella group.
Regarding my non-classical music tastes, I think (like many others) that are songs worth listening to in pretty much every genre, although I tend towards the rich harmonies and sounds of folk and indie rock. Sufjan Stevens is a favorite, as are Death Cab For Cutie and Fleet Foxes.