Balsa is an asynchronous circuit simulation and synthesis system. Balsa is built around the Handshake Circuits methology, and it can generate gate level netlists from high-level descriptions in the Balsa language. Both dual-rail (QDI) and single-rail (bundled data) circuits can be generated.
Electronic Engineering Tool is a Web-based tool that includes an electronic formula calculator and converter functions. It very useful when working with electronics, both for engineers and amateurs. For example, it includes converters for dBm-to-Watt and Fahrenheit-to-Celsius, and it can calculate Ohm's law, filters, thermal resistant C/W, SWR, coil inductance, capacitor capacity, and more.
libmls is a library that can be used to measure the frequency response of a loudspeaker or a room using your computer and an ordinary soundcard. It can perform both MLS (Maximum Length Sequence) and Sinus sweep measurements. It supports ALSA, OSS, and the sound system used in Windows.
JCCad is a project to develop a 2D/3D CAD program that can be used to create technical drawings. One of the main goals of this project is to include a plugin system to allow usuaries to make new commands. In this way it will be easy to use the program for any particular task. JCCad provides an easy interface with a command line.
YaPIDE aims to be a fully featured Microchip PIC simulator for Linux (and probably other Unixes). It is a GUI that provides a viewer for RAM, ROM, stack, breakpoints, and watchpoints, and has a source editor with inline debugging (ASM). The chip currently supported is the 16F628 (partial).