EarMaster - Professional software for ear training and practical music theory on Windows and Mac.
VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Meludia - Listening exercises and to sharpen your ear and music theory skills
foobar2000 - An advanced freeware audio player for the Windows platform.
GNU Solfege - GNU Solfege is free music education software.
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.