TweetSentiments

TweetSentiments performs semantic analysis of tweets using a Support Vector Machines algorithm. Doing so, it is able to determine whether tweets are positive, negative or neutral in sentiment. This data is provided on-demand by the TweetSentiments API.
TweetSentiments

Google Shopping Search

Google Shopping Search lets developers create applications to search for products. Developers can create product comparison apps or provide search and discovery tools for users. The API simplifies access to product data and is optimized to deliver the most relevant product results.
Google Shopping Search

DataSift

From website: DataSift provides very granular and modular 'sifting' functions from across a wide range of social and web input feeds, augmenting them with sentiment analysis, storage and analytics to offer an unrivalled service platform, which leverages the cloud and scales infinitely. The DataSift API allows developers to consume filtered data from DataSift, and edit various resources hosted on the site. Some parts of the API do not require authorization, others recommend authorization, and the rest require authorization.

DoIt

DoIt is an online Time and Task management service, with online service and Mobile apps. The DoIt API is a RESTful API that lets users access their DoIt data through GET or POST HTTP requests. The API lets users create and view tasks, view their contacts, and view their projects.
DoIt

Geni

Geni is a website centered around genealogy. Users can create their family tree, and invite relatives to help. The Geni API provides the API users with access to Geni's data. If the data is public, no API key is required to access it. Only private data requires authentication to access. Data is returned in JSON or XML format.
Geni

Opt It Mobile

Opt It Mobile is a mobile marketing application. The Opt It Mobile API is a RESTful API that allows developers to build their own applications around Opt It Mobile's tools. Data is returned in either an XML or JSON format. Through the API, users can create and manage Subscriptions, Keywords, Interests, Members, and Send Messages to their members.
Opt It Mobile

Divinity Shopping Cart

Divinity Shopping Cart API provides tools for 3rd-party developers to interact with the Divinity service. The Shopping Cart API is a RESTful API, with data returned in either XML or JSON format. Currently, the REST API URLs require HTTP-Auth to use, but there will be ReST API URLs ("ReST Servers") which do not require authentication (going to be public), for example getting a list of the top sellers, or the items from a category, etc.
Divinity Shopping Cart

Munin Exchange

Munin is an installable networked resource monitoring tool. Munin Exchange is a plugin repository for Munin. The Munin Exchange REST API allows developers to access data about the plugins stored in Munin Exchange through HTTP-formatted requests; API keys or signatures are not required for retrieving data, returned in JSON (default) or XML format.
Munin Exchange

IdeaScale

IdeaScale is a website that hosts communities in order to facilitate the discussion of ideas, companies, organizations, etc. Some companies use IdeaScale as a crowdsourcing platform. The IdeaScale API provides methods for obtaining data from the IdeaScale website for using in mashups and other consumable formats.
IdeaScale

Open State Project

The Open State Project API, provided by Sunlight Labs (part of the Sunlight Foundation), is part of the Sunlight Labs community of open source developers and designers dedicated to opening up our government to make it more transparent, accountable and responsible. The Open State Project API is a RESTful API for accessing state legislative information in a JSON format.
Open State Project