FluidDB

"FluidDB is a single web of things providing a no-questions-asked writable social object to represent each and every thing. Using a flexible underlying representation of information and a new model of control, it allows users and applications to work with information without constraint. That includes dynamically organizing, sharing, combining and augmenting information, and searching in ways that have previously not been possible. It also allows users to choose exactly which information to share with whom, with separate controls for reading and writing." "FluidDB makes it possible for data to be social. It allows almost unlimited information personalization by individual users and applications, and also between them. This makes it simple to build a wide variety of applications that benefit from cooperation, and which are open to unanticipated future enhancements. Even more importantly, FluidDB facilitates and encourages the growth of applications that leave users in control of their own data." The FluidDB API makes it possible for developers to create their own apps that can programmaticaly search the FluidDB datbase.
FluidDB

Mixcloud

Mixcloud is re-thinking radio by joining the dots between radio shows, Podcasts and DJ mixes. The Mixcloud API allows developers create applications that can search the Mixcloud database, upload 'cloudcasts', and get the code to embed the Mixcloud widget in a webpage.
Mixcloud

Cadmus

Cadmus is a real-time service that manages your stream (Twitter, FriendFeed and RSS) by displaying the most relevant content since the last time you checked in. It helps you get caught up on what you have missed. You can access Cadmus simply by signing in using your Twitter account or by using the API that allows you to view your filtered stream anywhere.
Cadmus

Peoplebrowsr

The PeopleBrowsr API contains over 1,200 days of social metadata from Twitter, Facebook, and Blogs/Forums for any keyword, #hashtag, user (@name), or combination of terms. Go deeper through specifying call structures with location, bio, gender, or sentiment. Method / Resource Directory: Mention Count - A histogram that returns the number of times a term has been mentioned Mentions & RTs - This option returns a histogram of retweets and total mentions. This is a meta-chart. It calls mentions and popularity and remaps labels: mentions -> total and popularity -> retweet Density - The number of posts and unique users posting about a term (“voice” vs "unique voices") Word Cloud - Top words in posts mentioning the term, ordered by frequency Hashtag Cloud - The top hashtags in posts mentioning the term, ordered by frequency @Name Cloud - The top @names in posts mentioning the term, ordered by frequency Friends and Followers - A histogram of followers and friends (following) counts for each date. Term must = user:name to specify an @name; entering @name will produce unexpected results. Counts are retrieved only from posts that the user has made during the date range specified Top Followers - Top @names mentioning the term, ranked by number of followers Positive Top Followers - Top @names mentioning the term in positive posts, ranked by number of followers Negative Top Followers - Top @names mentioning the term in negative posts, ranked by number of followers Popularity - This option returns a histogram of retweets or likes for a particular term Sentiment - The negative, neutral and positive sentiment calculated from posts matching the query Top US State - The top US States out of the posts mentioning the term, order by frequency. This information is gathered using a combination of the user’s location field, and geo data, if enabled by the user Top Countries - The top countries out of the posts mentioning the term, order by frequency. This information is gathered using a combination of the user’s location field, and geo data, if enabled by the user Top URLs API - The top urls in posts mentioning the term, ordered by frequency Top Pictures (TwitPics) - The top twitpic.com links in post mentioning the term, ordered by frequency Top Videos (Youtu.be) - This option returns the top youtube links in posts mentioning the term, ordered by frequency. Note the urls are in the shortened "youtu.be" format.
Peoplebrowsr

Zootool

Zootool is a webservice that lets users collect, organize, and share their favorite images, videos, and documents from all over the web. The Zootool API lets developers build their own applications around Zootool's tools. Developers can access user information, such as friends, followers and items. In addition, the API provides access to detailed item data, including the number of views and likes. Applications can also add new items to the Zootool database.
Zootool

Transifex

"Transifex is an open service allowing people to collaboratively translate software, documentation and other types of projects. Designed as a hub for translations of open source projects, Transifex supports translations straight from the project's source." The Transifex API is a RESTful API that allows developers to build their own applications using Transifex's tools.
Transifex

Weplay

Weplay is a youth sports community that connects youth athletes, parents, and coaches. Weplay offers an API that lets developers create applications that can access Weplay (update/retrieve/delete data) through HTTP calls to the API endpoint. Data is returned in an XML or JSON format.
Weplay

Petfinder

Petfinder is a website that lets users search for pets that are up for adoption. Petfinder also offers a RESTful API that allows developers to create their own applications that query the Petfinder database. Searches can be by breed, pet, shelter, or by breed/pet at a specific shelter.
Petfinder

Bentio

Bentio is a Twitter-like open source microblogging service. The Bentio API is a Twitter-like API that is intended to allow applications that communicate with Twitter to also communicate with Bentio.
Bentio

Joliprint

Joliprint is a webservice that converts HTML webpages into PDF documents. Joliprint also provides a free RESTful API for developers to integrate Joliprint's service into their own applications. In addition to converting webpages into PDFs, Joliprint's API can also provide an XML/JSON document that describes the PDF, a JPG thumbnail image of the PDF's 1st page, or return a short URL to link to the converted PDF.
Joliprint