FullContact4j is a Java client made for interfacing with the FullContact contact management APIs. The Java client can be used to invoke the Person, Email, Name, Location, Card Reader, and Account Statistics FullContact API endpoints. Now in version 2.0, FullContact4j 2.0 offers customizable clients for easy execution. It's dependencies include OkHttp, an HTTP client, Retrofit, and Jackson, a JSON library for converting API responses.
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.