Clementine

This is my preferred Audio organizer/player on Linux. Unfortunately, there is some kind of bug in the code that causes it to amp up to 100% cpu usage when it is closed when using an Nvidia graphics card. I know, weird, but it's been present through several Nvidia driver updates and has caused me to use Guayadeque as a replacement on my main box. Shame, I really like Clementine, but issuing a killall command everytime I shut the thing down is a pita.

Edit: Thankfully the developers fixed this bug and I'm back to using Clementine, at least on a part-time basis. Unfortunately for them, in the interim I had an opportunity to test several other clients and have gotten accustomed to Guayadeque and Gmusicbrowser, especially the incredibly high level of customization available to the latter, so Clementine has more or less taken a back seat.

This is the best sounding MP3 player for Windows I have found. A little background - I was happy playing my mp3's on Windows until a gave Ubuntu a go on a spare partition on my PC. I used the default mp3 player on it (Banshee) on was surprised at how better the music sounded - more clarity,depth, spatiality. On going back to Windows I tried just about every other MP3 player but they all sounded similar and a little dull compared to Linux even when using WASAPI sound. I thought that maybe it was because it used different soundcard drivers on each OS but then I found this player which uses the same GStreamer library from Linux on Windows and it now sounds as good. So it must be the GStreamer library produces better quality.

Great, lightweight and fast music player on OSX with many features. Forget bloated iTunes!
Player is actively developed.

My new Amarok 1.4 :D

Works great on all my platforms!

Give it a try

Good interface, nice features, but the performance is kinda bad.