The Helioviewer Objective-C SDK by Helioviewer communicates with the API to access solar data visualizations. Installation is available via GitHub and CocoaPods. Guides explain how to make asynchronous requests to receive code responses.
Swivel, along with its cousin IBM Research's Many Eyes, is helping make sharing, visualizing, and discussing data on the web fun and addictive. How? Take, for example, the following Swivel-hosted graph, which shows the Growth of Creative Commons Photos on Flickr to millions of photos.
RESTful services that underpin many Web APIs today should follow design patterns that make any Web API a good Web API. Such design patterns are all about respecting HTTP protocol specifications, respecting good URI design principles, or taking the full advantage of underlying Web infrastructure for Web API's good performance and scalability. If you are interested in such practices or in a cutting-edge research that may impact the future of Web APIs developments, you should look into the series of workshops on RESTful Design.