doubleTwist - Music Player for the Internet of Things. Described as the iTunes for Android, doubleTwist brings you music, radio and podcasts everywhere. Free download.
VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
iSyncr - iSyncr lets you sync iTunes playlists with your Android phone.
foobar2000 - An advanced freeware audio player for the Windows platform.
SYNCiTunes - Do you have an iPod, but you don't like to use ITunes for managing your audio files?
Winamp - Winamp is a media player that allows users to play multiple-file formats, arrange media in a varied file-management system, and play unique media with AAC encoding.