Cymbal - Music discovery powered by friends
BookWidgets - BookWidgets is an excellent application that let you create engaging exercises in minutes and easily share a varied variety of beautiful and fun activities with your classroom and others.
humit - A social networking app for music sharing and discovery.
Padlet - Visual boards for organizing anything.
Better Notes - Simple notes app that ties notes together with #hashtags
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.