Install Virtual MIDI Piano Keyboard on Ubuntu Linux | VMPK | Free Piano Keyboard on Computer - YouTube
LAA] Mamba - Virtual Midi keyboard for Jack Audio Connection Kit release 1.4 - LinuxMusicians
Ted's Linux MIDI Guide
Play Midis on Linux / Make Linux MIDI Ready for the Future - Enable embedded MIDI music to play in a Browser, Play MIDIs with VLC and howto enjoy Midis in Text