Solve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.
EMSO simulator - EMSO simulator is an equation-oriented process simulator with a graphical interface for modeling...
simavr - a lean and mean Atmel AVR simulator for linux
StochSD - StochSD (Stochastic System Dynamics) is a Continuous System Simulation extension that is built with the capabilities to help you simulate continuous flows between compartments and, most importantly, also has the power to manage discrete transitions …
Emulino - an emulator for the Arduino platform by Greg Hewgill
Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.