The UStream Player iOS SDK by UStream allows to interact with the API, providing applications the streaming feature of live and recorded videos. With the SDK, developers can customize and callback on status changes. They also have the alternative to work with the HTML based player API.
Did you ever want to have a quick-and-easy way to test-out an API without having to write code? Now with the YouTube API you can. They now offer developers this web-based interactive form which lets you explore and interact with the YouTube API. You can setup and test API calls directly: choose operations, specify parameters, and see the Atom, RSS or JSON results.
If you want to see in realtime what's going on Digg you can use their digg spy page. This popular Digg feature uses a dynamic Ajax UI to let you see diggs as they happen. And now it serves as a model for a growing number of mashups that use web APIs to give you a realtime window into activity on a variety of services.