Notation Pad - Notation Pad is the Easiest way to write sheet music with notations on iOS/Android.
Angle Finder™ - Angle Finder™, now rebranded to Protractor+, is an app that offers a handy protractor tool on your phone.
Orpheus App - Sheet Music Reader for Android
iHandy Carpenter - An handy carpenter tool kit right on your device! There are 5 tools in this Carpenter tool kit:
Symphony Pro - Complete music notation and composition app for iPad.
iLevel – Protractor & Level - iLevel – Protractor & Level, now named Measure Angles – Level, is one of the most precise and easy-to-use clinometer and leveling apps that allows you to quickly and easily measure angles, slopes, and distances.