The Issuu Java SDK by Christophe Ribeiro is a work in progress to interact with the document publishing features of the API. However, it does include resources to access Key and Secret for testing purposes.
Wolfram Alpha, the up-and-coming "answer engine" that we reported on back in May, has just released an API that developers have been awaiting since this spring. The new RESTful API provides access to the vast stores of data and computational knowledge available through the Wolfram Alpha project (technical details at our Wolfram Alpha API profile).
Gravity, focused on personalizing the internet, has launched a new series of free APIs to further its mission. The APIs enable web publishers to recommend content to users in addition to sponsored stories from paying advertisers. Prior to the API offering, Gravity tools provided recommendations based on demographic and interests through widgets and home page personalization. The API should expand Gravity's reach into mobile apps and deeper web adoption.
Search Engine Optimization, or SEO, is vital to any successful website. The team at SEOmoz are experts in this field and now offer a number of premium SEO tools including the recently released Open Site Explorer, which provides a wealth of information on backlinks and link popularity. Now the same information available through Open Site Explorer can be accessed via their new API.