Knowledge Should be Free!
All our own, and many commissioned, designs are created under the Creative Commons Attribution-NonCommercial 3.0 license. This allows you to take our board designs and expand upon them. All we ask in return is a nod in our direction as the original designers.
Not only is the majority of the software we write open-source (released under the BSD 3-clause license) but in-house we only use open-source software. That includes all our EDA tools, such as the gEDA suite.