MusicBee is my favourite music manager and player, on any platform. It leaves the most of the open-source players in the dust. Once upon a time, Amarok 1.4.10 beat its ass, but that turned to muck when the developers threw the baby out with the bathwater in the 2.x releases. Unfortunately the MusicBee developer, Steven Mayall, doesn't want to open source the code. However, I've seen what can happen when a perfectly decent project gets too much input, and Steven's doing a fine job of developing the player single-handedly. Some people are worried that he'll get hit by a bus before he gets the chance to share the code, and of course that would leave the community without the means to continue developing it. But it doesn't look like Steven's going to open it up any time soon. At any rate, according to Steven, porting it to Mono would be a nightmare, and right now it's very usable on Wine.

Disclaimer:
Never download a script from the internet and run it without first checking it. In other words, run the first two lines and then read through the musicbee_installer.sh to make sure you're OK with everything it's doing. I'm not trying to break anybody's computer, but I offer no warranty/guarantee and take no responsibility for any trouble it gets you into. I'm simply sharing something that I wrote.

Enough of the crap, here's how to install the latest MusicBee (2.2 beta) on Ubuntu: