open-source-rover - A build-it-yourself, 6-wheel rover based on the rovers on Mars!
The DIYLILCNC is a fully functional, open source 3-axis CNC that you can build with basic tools and parts that can be locally sourced. The idea is that you develop a 3D design in a CAD application, put feedstock into the CNC, and print your design to it, and it cuts and grinds away everything but what your design is supposed to be. Total cost of construction is about $700us. You can download the plans and DXF template files from the website for free (they have a CC-BY-SA license).
Open Ephys is a site that catalogues open source neuroscience hardware - EEGs, data acquisition boards, EMGs, and other bits of equipment that manufacturers historically never manufactured very well.
A utility that reads the data from magstripe cards and tells you what's on them.