iCircuit - Its advanced simulation engine can handle both analog and digital circuits and features realtime...
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
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
PCBWeb - PCBWeb is a 100% free Windows desktop CAD application for designing and manufacturing electronics...