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.

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.

itom - itom is an open source software suite for operating measurement systems, laboratory automation and...

QUCS - Qucs, briefly for Quite Universal Circuit Simulator, is an integrated circuit simulator which means you are able to setup a circuit with a graphical user interface (GUI) and simulate the large-signal, small-signal and noise behaviour of the circuit.

PyLab_Works - PyLab_Works is a free and open source replacement for LabView + MatLab, written in pure Python.

FlowStone - FlowStone - the new graphical computer programming tool that allows you to create your own standalone programs quicker and more easily than ever before, download for FREE!