I've been prototyping a service to extend the data available about any organisation identifier used in IATI activity documents. This includes data about the 'realm' or namespace of the identifier as well as about the referenced organisation itself.
For example GB-COH-7676886 is a structured code used in IATI. The URL
http://opencirce.org/org/code/GB-COH-7676886
or
http://opencirce.org/org/realm/GB-COH/code/7676886
provides information about the realm (GB Company Numbers) and sites which provide information about this realm, and information about the specific organisation ,"Publish What You Fund". This includes the name (taken from the xml feed from OpenCorporates) and links to the relevant pages on CompanyHouse and OpenCorporates.
The application itself contains no organisation data. Instead it contains descriptors of the realms in an XML document, with templates to derive the URLs of related pages. Currently there are six 'realms' described with varying degrees of detail.
UK and US companies and charities can be linked quite well. However DAC identifiers are more difficult. These codes are defined by the Development Assistance Committee of the OECD for their report and have been adopted for use in in IATI . They identify over 400 government departments and NGOs but the OECD data provides only the name and abbreviation of the organisation. I've appealed for further information on these codes on getthedata.org but have also started my own project to gather at least websites. I'd be pleased to hear from anyone who could help with this task.
Of course none of this would be possible without the wonderful work of the data warriors behind OpenCorporates and OpenCharities.