1 Data
This posts lists some great open-access data sets of public or broad interest. This list is by no means comprehensiv, it’s just a casual curation of interesting sources. Note that this post is not updated, so more frequent releases than documented here are possible.
You’ll find both links to repositories as well as to particular datasets, in no special order.
1.1 Licences
I tried to locate sources with permissible licences only, such as CC BY. But note that some or many of the following data sets may have a non-commerical licence of a completely different licence.
Check for yourself! I do not take any responsibilities.