I'm involved with Bath Hacked (UK) a community interest company set up in partnership with the local council which actively hunts out council data sets that can be published in the data store.

The site: https://www.bathhacked.org/ The data store: https://data.bathhacked.org/

We run hackathons and also reach out to various organisations for data sets that although we may not be able to publish in the datastore, can result in very interesting tools.

The most recent data we got our hands on was the bike share hire programme. https://www.youtube.com/watch?v=4AfocuESnSg