i still use winamp on my main desktop. on my work mac, i tend to use VLC. i do not like itunes. it's been a long time since i've needed to listen to music on a *nix machine. i typically have my rockboxed ipod handy anyway.

plus soundcloud, youtube, bandcamp, mixcloud, etc, of course. but for stuff in my collection, it's usually winamp, the ipod, or vlc.