VoltSim - VoltSim is an interactive realtime circuit simulator. It has digital and analog components and even Integrated Circuits. It is the perfect companion to students, hobbyists, and engineers.
Circuito.io - Instant code and wiring for your project
Diode - diode - Android app to interact with reddit.
Quip - Quip is the modern productivity suite that simplifies your life and helps your team get work done faster.
PhET Interactive Simulations - Founded in 2002 by Nobel Laureate Carl Wieman, the PhET Interactive Simulations project at the University of Colorado Boulder creates free interactive math and science simulations.