NPM is a great resource for finding packages: Node Package Manager
- Protocols: Socket.io | Mosquitto | Github Hooks
- Logging: Morgan
- Data Viz: D3.js | chart.js
- Canvas: canvas | THREE.js | AFRAME
- Games: Phantom.js
- Build Tools: Grunt | Gulp | Webpack
- Polyfills: Modernizr
- Frameworks: Ember | Angular | Polymer | Vue
- Texting/Phone Calls: Twilio
- Testing: mocha/chai | jasmine
- Documentation / Linting: jsdoc | jshint | jslint
- Database/ORM: bookshelf.js
- A/B Testing: Optimizely | ab-testing | express-ab
- Other Flavors of Javascript: TypeScript | Elm | coffeescript | Closure Compiler
- Templating: Handlebars.js | Mustache.js
- Productivity Tools: any atom extension
- Payments: Stripe | Paypal
- Email Sending: Sendmail | Mailgun
- Built In / Newly Supported Features: localStorage | pushState | serviceWorkers | WebAudio | WebRTC | WebComponents
- Benchmarking: benchmark.js
- jQuery plugins: Autocomplete, jQueryUI, Draggable, Droppable, Resizable, Selectable, Sortable