I have a FreeNAS server set up at home for most of those services. It's a FreeBSD based distribution focused on file services, but you can really run any service from the BSD jail system. FreeNAS comes with click'n run plugins for a lot of the services mentioned in this thread: ownCloud (files), firefly (music), btSync (files), Plex (video/music), Subsonic (music) and more.

Now a Mac Mini isn't the most fearsome server, so you won't get extraordinary performance, but it should perform good enough for for 1-2 concurrent users.