Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.
Piano Visualizer - Bring your piano music to life with this application.
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
Piano Connect - Piano Connect is one of the most popular piano learning apps that helps you play piano on your smartphone anywhere at any time.
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
Chordana Play for Piano - Chordana Play for Piano is an app that allows you to learn piano with any MIDI-supported keyboard or the actual MIDI piano.