The APIs can be used for all of the types of apps you mention -- there's nothing limited to, or even targeted to advertising. Here's an idea for an app: Imagine that you're a non-native English speaker, and you want to communicate with English-speaking friends on Facebook or Twitter. Language identification can detected your language, machine translation and translate it to English, concept expansion can automatically generate potential synonyms, message resonance can select the synonyms that best capture your message, and user modeling can tell you what kind of emotions your message is communicating. This technology can and will be used to bring people together, but ultimately it comes down to what types of apps people make.