iCircuit - Its advanced simulation engine can handle both analog and digital circuits and features realtime...
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
Altium Designer - PCB Design Software
Solve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.