LabVIEW - LabVIEW offers many of the functions you'd find in a traditional script-based programming language presented in a more intuitive visual interface ideal fo engineering.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
myOpenLab - MyOpenLab is a platform for finished elements (program components) that can be linked together.
Fritzing - Fritzing is an open-source initiative to support designers, artists, researchers and hobbyists to...
PyLab_Works - PyLab_Works is a free and open source replacement for LabView + MatLab, written in pure Python.
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.