Sibelius - Sibelius is a virtual score creation tool which allows composers to easily create new piano scores, developed by Avid.
iHandy Carpenter - An handy carpenter tool kit right on your device! There are 5 tools in this Carpenter tool kit:
Orpheus App - Sheet Music Reader for Android
Angle Finder™ - Angle Finder™, now rebranded to Protractor+, is an app that offers a handy protractor tool on your phone.
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.
Pocket Ruler AR - Pocket Ruler AR is a pocket ruler app that lets you measure objects and distances with your phone.