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.
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.
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
Oregano - oregano - An electrical engineering tool for GNOME