> The best way to contribute is to openly license government datasets

Second best way to contribute is to force commercial corporations to share the datasets they have of what is essentially public data - what is in the physical world and where. Currently, I see a lot of this kind of data on Google Maps, but not on OSM (e.g. location of various cultural and commercial venues, public transportation lines and schedules etc.)

And by "force" I mean something like legislation or regulation.