pegboard is a social bookmarking service that lets you save, search, share and tag your bookmarks with people all over the world!
JSON Data API documentation from the chicago schools report.
census.ire.org's JSON API documentation
Messaging APIs. A twilio competitor but with (limited) international coverage.
Saplo's Text Analysis API can provide context, sentiment, and other extracted information from a body of text.
Google's places API has over 100 globally-consistent place types.
Serves as the data hub for the HHS Community Health Data Initiative by providing a single source for national, state, and community health indicators. Map, graph, download or view indicators by geography, topic or initiative.
Syntax highlighting for your code. Anywhere (that can post to this API).
Web app for compiling your coffeescript files. It'll minify the result too, if you want.
Docs for Salsa's simple script and authenticated external APIs.
A web application for analyzing your ecommerce or subscriber customer base and then figuring out how to keep those customers.
A how-to on using the twilio API from within your node.js application.
Yes, Please cluster my markers for me easily and quickly!!
Create PDFs from web content. (They have an API.)
Allow your application to receive mail via this app/api.
Web-based point-of-sale with inventory management and some other really nice features, including a full API.
"What would encourage you to walk, bike, and take CTA more often?"
A payment gateway whose API, reportedly, "does not suck".
Build a (mobile) social networking application for your community.
Web Service API for building Voice and SMS Applications
Technogeeks with a nice solution to having one CakePHP application authenticate a user (and thus accessing data) from a different CakePHP application.
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