Google Play Music Desktop Player - A beautiful cross platform Desktop Player for Google Play Music
VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
GDeskTunes - Multi Platform Desktop Player for Google Play Music™ that integrates beatifully in your OS.
foobar2000 - An advanced freeware audio player for the Windows platform.
Nuvola Player - Cloud music integration for your Linux desktop.
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.