Folks interested in "open knowledge" should check out CKAN (Comprehensive Knowledge Archive Network)
CKAN is the Comprehensive Knowledge Archive Network, a registry of open knowledge packages and projects (and a few closed ones).
The World Bank, whose mission is to end world poverty by providing financial and technical assistance to developing countries around the world, is now offering developers a new API (our World Bank API profile).The bank considers the development of its API a component of this mission.
Wolfram Alpha, the up-and-coming "answer engine" that we reported on back in May, has just released an API that developers have been awaiting since this spring. The new RESTful API provides access to the vast stores of data and computational knowledge available through the Wolfram Alpha project (technical details at our Wolfram Alpha API profile).