yeah, SubFire is an app I wrote (insert shameless plug
) for playing your music on the FireTV. Free (though you need the premium license of Subsonic itself to use apps). Supports all browsing methods except 'starred' - playlists, folder structure, album queries (akin to the 'home page'), and artist->album by id3. It plays directly on the TV/Stick, no 'cast' required.
Even works well if you take your stick with you to a hotel - I do that all the time - provided you've opened your ports properly in your home firewall/router.
The only 'bug' I can not really fix is that if you have an unsigned/self-signed SSL cert, SubFire can not talk to that server. This is a limitation on the FireOS platform and there is no workaround other than signing your cert (along with keeping it up or making sure the domain you reference is the domain the cert is authorized for), or going with plain http.
More details at the webpage below.