I have used MPD on linux on a remote computer to playback audio remotely. There are web based clients as well as native clients for multiple operating systems (mostly *nix systems though) for controlling MPD. I used PulseAudio as the sound server because it was the easiest to set up and was already installed on the linux distro i had.
Tutorial for using MPD with PulseAudio - http://mpd.wikia.com/wiki/PulseAudio
MPD clients - http://www.musicpd.org/clients.shtml