Alchemy is an open drawing project aimed at exploring how we can sketch, draw, and create on computers in new ways. Alchemy isn’t software for creating finished artwork, but rather a sketching environment that focuses on the absolute initial stage of the creation process. Experimental in nature, Alchemy lets you brainstorm visually to explore an expanded range of ideas and possibilities in a serendipitous way.

Coccinella is a free and open-source cross-platform chat client with a built-in whiteboard for improved collaboration with other people.

Xara Xtreme for Linux is a powerful, general purpose graphics program for Unix platforms including Linux, FreeBSD and (in development) OS-X.

The gEDA project is working on producing a full GPL'd suite of Electronic Design Automation tools

The ElectricTM VLSI Design System is a complete Electronic Design Automation (EDA) system that can handle many forms of circuit design.

A Web2.0 collaborative diagramming application