VLC Media Player - VLC is a free and open source cross-platform multimedia player and framework.
Knowthelist - Knowthelist - the awesome party music player Easy to use for all party guests
MPV - MPV is an audio and movie player based on MPlayer and mplayer2.
MixTape - Home of MixTape, an OSX application for creating beat matched mixes with simple export to the web or iTunes.
SMPlayer - SMPlayer is a free video and audio player for both Windows and Linux that allows you to play almost all media files without having to install additional codecs. Read more about SMPlayer.
Song Director - Song Director is a program that plays and keeps track of all your music files.