Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
Abundant Music - Generate royalty free music with a simple but very powerful procedural music creator
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.
AIVA - The AI composing emotional soundtrack music
Finale - Finale, the world standard for music notation software, lets you compose, arrange, notate, and print engraver-quality sheet music.
WolframTones - Listen to what I just found in the WolframTones music universe