Pspice - OrCAD PSpice technology provides the best, high-performance circuit simulation to analyze and refine your circuits, components, and parameters before committing to layout and fabrication
Solve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.
Oregano - oregano - An electrical engineering tool for GNOME
PCBWeb - PCBWeb is a 100% free Windows desktop CAD application for designing and manufacturing electronics...
BlackBoard Circuit Designer - Help building prototypes on so called breadboards easily
Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.