After years of using free software and singing the praises of the open source community, I have finally contributed by open sourcing a MATLAB toolbox which I co-wrote with other members of the Nottingham nanoscience group.
The toolbox is called SPIW, standing for: scanning probe image wizard (See also my local page on SPIW). It can be used to automate many image analysis tasks which scanning probe microscope (SPM) users regularly do by hand. The idea is that by opening up the code to the community it will help many SPM users, and that others will contribute to make SPIW better.
One could argue that writing an open source toolbox for a proprietary computing environment does not fully agree with the goals of the open source community. However, MATLAB is used by most universities across the world, and makes it very simple to modify and improve code compared to compiled programming languages. Perhaps the future will bring a C++ SPIW dll, or maybe an Octave port of SPIW, but currently I am proud to announce SPIW for MATLAB.