I’ve just read about Tomahawk player at http://www.linuxjournal.com/content/tomahawk-world-your-music-collection
Looks like somebody is finally uniting music lovers not limiting them to a specific music provider.
The social stuff via Gtalk or custom XMPP (Jabber) is promising.
YouTube plugin that will search YouTube for songs, but it isn’t included by default, available free install from nightly builds. More info at https://github.com/tomahawk-player/tomahawk-resolvers
Handy bookmarklet for grabbing songs from websites available at http://toma.hk/tools/tomahklet.php
Settings of bookmarklet
Click Save playlist to Tomahawk and it fetches the songs