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.

productboard - Beautiful and powerful product management.

Circuit Simulator - Animated electronic circuit simulator using ideal components to visualize voltage and current.

Aha - Aha! is the new way to create visual product roadmaps. Web-based product management tools and roadmapping software for agile product managers.

Solve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.

ProdPad - ProdPad helps your team gather ideas, surface the best ones and turn them into product specs, and then put it all on a product roadmap.