Windsoc is a service that allows users to get and share data in a uniform way across various sources. Users can pull data in such as activities, followers and profiles and they can share links, messages, comments, tweets and more. The data sources include facebook, flickr, twitter, foursquare, linkedin and many more. The API uses RESTful calls and the responses are formatted in JSON or ATOM using the ActivityStrea.ms format.
Uberblic is another instance of what may become a trend in the world with thousands of APIs: the Meta-API. The Uberblic Doppleganger API is currently in beta, but it is quite ambitious in that it looks to position itself as a API cross-reference or mutli-plexer. Submit an ID from one API to the Doppleganger, get 4-5 IDs for matching content from other APIs.