Vue
Intuitive, fast & composable MVVM for building interactive interfaces.
Pure
PURE Unobtrusive Rendering Engine for HTML
Superagent
Ajax with less suck - (and node.js HTTP client to match)
Contra
Asynchronous flow control with a functional taste to it
Csso
CSS-optimizer
Bem Core
BEM Core Library
Tangle
a JavaScript library for reactive documents
Jade
Jade - robust, elegant, feature rich template engine for nodejs
Serenade.js
Client side MVC framework
Invisible
Invisible.js: Reusable models for the client and the server
Backbone.stickit
Backbone data binding, model binding plugin. The real logic-less templates.
Modules Webmake
Bundle CommonJS/Node.js modules for web browser
Componentjs
ComponentJS -- Powerful run-time Component System for structuring HTML5-based Rich Clients
Backbone Deep Model
Improved support for models with nested attributes.
Transparency
Transparency is a semantic template engine for the browser. It maps JSON objects to DOM elements by id, class and data-bind attributes.
Bacon.js
FRP (functional reactive programming) library for Javascript