The World Bank has recently released their first API. The original description of the data gives a good overview:
The World Bank API offers developers information contained in the most popular World Bank databases. From projects to data and photos, you can access information by country, by type or by topic.
The included sources are:
- The Little Data Book 2008 (WDI)
- Worldwide Governance Indicators
- Doing Business
- The World Bank Photo Library
The API has a extensive documentation which makes it easier to get started.
To access the data you need to register and apply for an API key. The data can be used on non-commercial applications that needs to be branded using one of the original logos of The World Bank. The license sounds good to me and the obligatory logo may also have an effect on the credibility of the application. Although a downloadable dataset would have been nice too.