The Guardian’s new World Government Data site collects data from the UK (including London), the U.S., Australia and New Zealand. Currently, the repository includes 19 different sites, and the media outlet plans to add more as they become available.
Most important for developers, the Guardian has also made an API available so that applications can compare data from different countries, even though those datasets are usually in different formats.
Users are also invited to rank the datasets based on their quality.