And then, there's also ConceptNet (http://conceptnet5.media.mit.edu/)

This seems interesting. Code for building ConceptNet5 [0].

[0] https://github.com/commonsense/conceptnet5

Anybody managed to get an API key for this service ? Seems that http://developer.here.net/myapps (which is linked elsewhere in the site and looks like the url for a developer dashboard) is broken (even when you're signed in or at least trying to sign in with a legit nokia developer account).