DeaDBeeF is an audio player for GNU/Linux systems with X11 written in C and C++. Features: minimal depends; native GTK2 GUI; cuesheet support; mp3, ogg, flac, ape; chiptune formats with subtunes, song-length databases, etc; small memory footprint.
Core part is GPLv2-licensed, while plugin header uses zlib/libpng license. This allows to write plugins using pretty much any license.