The Evernote Windows SDK by Evernote allows to interact with personal information management features of the API. Windows users can benefit from the creation and usage of apps that could simplify life & work organization. Resources include setup with steps to register for an API Key or Token, include the library in the app, modify the startup code, and see the project in action.
MyBantu is an interesting little mashup, available as an iPhone app, an Android app, and a website. Its goal is to make shopping for anything, especially restaurants and movies, easier and more social. It uses Yelp API, Netflix API and various others to make it happen. It's very similar in idea to Siri, the "ultimate mashup" that Apple later gobbled up in the largest mashup acquisition ever.
Our API directory now includes 34 tagging APIs. The newest is the Ontos API. The most popular, in terms of mashups, is the Zemanta API. We list 6 Zemanta mashups. Below you'll find some more stats from the directory, including the entire list of tagging APIs.