Virtual MIDI Piano Keyboard - Virtual MIDI Piano Keyboard is a MIDI events generator and receiver.

Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.

EveryonePiano - Everyone Piano is the best free computer keyboard piano software, which supports downloading 3 types of music score formats like stave, right and left hand numbered musical notation and EOP file.

MuseScore.org - Create, play back and print beautiful sheet music with free and easy to use music notation software MuseScore. For Windows, Mac and Linux.

Synthesia - A fun way to learn how to play the piano.

Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.