However, this puts me in a situation where I cannot join many otherwise interesting initiatives. There are many examples, but I will isolate one, for no particular reason other than that they just published an interesting paper about DMSO solubility modeling (doi:10.1021/ci400213d): the Online Chemical Database.
The training data from this solubility study is available from this website, and is listed in the abstract as freely downloadable. Well, free as in free beer. I cannot even look at the data set metadata without signing a license. So, I started reading the license, and clauses like this worry me:
4.1 The User grants to Helmholtz Zentrum Muenchen by submitting information, data, models and structures to the Online Chemical Environment a world-wide, non-exclusive, transferable and sub licensable right to use all information data, structures and models submitted, for research, teaching and any other (including commercial) purposes.
BTW, comparing this clause to 4.2 is awkward too. Not giving downloaders of data sets uploaded to the database the same rights as the uploader has given you, doesn't sound like being a good citizen.
Now, in no way this data base is unique. Many databases I encounter, all with the best of intentions, come up with legal obstacles. Is that really what you wanted to do?