There's an ALSA plugin that lets you route ALSA signals through it, so your applications don't
have to be changed at all. Works much more smoothly than ALSA dmix, so I'm definitely leaving
it turned on.
The only snag is that VideoLAN Client is not fully compatible with it (need to set the audio
device to the proper ALSA one manually). Last.fm's client is still hogging the ALSA device,
but that's a problem even with dmix.