gmusicbrowser is a jukebox designed with large music libraries of over 10,000 MP3, Ogg, m4a, FLAC, and MPC files in mind. It has easy access to related songs (same artist, album, or title) and supports multiple genres per song, ratings, and labels. It has extensive filtering capabilities, customizable random modes, customizable window layouts, mass-tagging, and more.
Virtual MIDI Piano Keyboard is a MIDI event generator and receiver. It doesn't produce any sound by itself, but can be used to drive a MIDI synthesizer (either hardware or software, internal or external). You can use the computer's keyboard or mouse to play MIDI notes. You can use the Virtual MIDI Piano Keyboard to display the played MIDI notes from another instrument or MIDI file player.