Expressive middleware for node.js using generators via co to make web applications and APIs more enjoyable to write. Koa's middleware flow in a stack-like manner allowing you to perform actions downstream, then filter and manipulate the response upstream.
Sails.js make it easy to build custom, enterprise-grade Node.js apps. It is designed to mimic the MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with scalable, service-oriented architecture.
Intuitive and Documented It is strongly influenced by jquery with many similar methods so you'll feel at ease developing with Umbrella. However there are also some improvements such as with .ajax(), .append(), etc.
Opa is an open source, simple and unified platform for writing web applications. All aspects are directly written in Opa: Frontend code, backend code, database queries and configuration. And everything is strongly statically typed.