There are many libraries that consume or provide promises. Here is a list of some of the more popular ones. Feel free to add to this list, providing a link and a short description.

• Process.js Multithreaded queue for JavaScript.
• Capsela A promise-based, high-level Node.js web application framework built for testability.
• Chai as Promised Extends the Chai assertion library with assertions about promises.
• Dynamo as Promised Promise-based interface to Amazon's DynamoDB
• Mocha as Promised Adds promise support to the Mocha test runner
• Q-IO I/O related Q utility funcitons: file system and HTTP client/server/middleware
• Q-Connection Communicate with remote objects via promises
• Qx A set of utility methods for working with promises of arrays of promises
• Joey HTTP route configuration based on Q-IO.
• QEJS Adds promises to EJS templating.
• Zanimo.js Animation library wrapping css3 transitions in promises
• Qajax A simple and pure XMLHttpRequest wrapper for ajax requests.
• q-xhr A port of Angular's $http service that uses Q for ajax requests with all the features and more.
• Qimage A simple Image wrapper for loading images.
• Qretry Retry an action until it succeeds after a max number of try and with intervals.
• redis-lock-q Port of redis-lock, which implements a locking primitive using redis in node.js.
• memoizer Redis backed multi-process safe locking memoizer, heavily inspired by redis-memoizer

Many other projects in npm use Q internally or provide Q promises.