About a year ago when we started the SpectralWorkbench.org website, this seemed like an academic question, but as our database of shared spectral data grows, I think it's time to ask what people think about how we license that data.
Right now, all spectra are public domain, so there is no requirement to attribute the data if you use it. I was persuaded to start it so liberally by Ethan Zuckerman, who made the case that SafeCast is doing the same thing, and that you just really don't want to limit what people can do with the data so it has the maximum potential to do good. We took a similar position when we did most maps of the Deepwater Horizon oil spill, and many folks continue to put their MapKnitter maps in the public domain (it's the default).
However, i want to point out that other open source projects such as OpenStreetMap and Wikipedia require attribution to their community ("ODbL OpenStreetMap contributors, 2012" for example) and OSM's license in particular is ShareAlike, which requires that "downstream" users release any additions under the same license.
Much has been made of this ShareAlike provision, and I wonder if we would do well to adopt it -- or at least a Creative Commons Attribution license -- for SpectralWorkbench, so that our work is properly attributed. If we went as far as a ShareAlike license, any additions to the dataset would be required to be released under the same terms.
Maybe this isn't important to you, but I feel like we ought to at least consider encouraging people to "give back" as they use our data, and at a minimum, to attribute it to our community. I'd love to hear your thoughts.