Lepton - Lepton image compression: saving 22% losslessly from images at 15MB/s
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.
3Cols - Manage your code snippets in the cloud fast, easy and free for personal use forever.
Padlet - Visual boards for organizing anything.
SnipAway - A customizable snippet manager made for developers and people who work with code
Quizlet - Quizlet allows you to review and create flashcards for a variety of subjects, such as math and reading.