Update : Rob Eisenberg (Creator of Durandal) has left AngularJS. He blogged the following recently:
Several months ago the general direction of Angular 2.0 began to change in critical ways. I found myself fundamentally at odds with certain aspects of the proposed design. Still, I tried to keep an open mind and explore the various possibilities. Unfortunately, I haven't been satisfied with how things have progressed since then. — Rob Eisenberg Source
React, the UI library by Facebook, is a great tool for developing User Interfaces. As you may be aware there are certain challenges involved in running Single Page Apps. The major one is SEO. But this can be solved by creating isomorphic apps. One of the best things about React is that it can render on both client and server which makes it an excellent choice for creating isomorphic apps. React, when used with Flux pattern, is definitely a bliss for developers. Popular websites like Facebook, Instagram, Khan Academy, New York Times and many more are using React. Having talked about its benefits and growing popularity I think React is going to be one of the popular web technologies in coming days.
Dart & AngularDart
Dart is an open source project by Google which aims to simplify web development. It can run on the web and server. Lately Dart has been getting developers' attention and it has been ported to AngularJS too.
Parse is a complete backend for mobile apps. It has got everything you need in the backend for your next mobile app. You can store both files and data in Parse and also send Push Notifications using Parse Push. As the number of mobile apps is increasing exponentially you can't ignore Parse in the coming year.
Update: Best of Parse 2014 — A blog by Parse team showcasing the best apps built using Parse in 2014.
Socket.io is a Node module that allows you to create realtime apps easily. According to Socket.io website it's being used by products like Microsoft Office, Yammer, Zendesk, Trello etc. Realtime apps are definitely cool and these types of apps are gaining attention lately. Socket.io makes creating such apps easy and enjoyable. I think we will see more usage of Socket.io in following year.
Polymer uses WebComponents to redefine web development. It allows you to build well encapsulated and reusable custom components that extend HTML. Component based development is definitely great and Polymer does it right. So, we can expect Polymer to grow and become developers' favourite in near future.
News : New Release — Polymer 0.5.2 — Dec 12, 2014
Gulp is a build tool that relies on code-over-configuration to keep build process simple. It heavily relies on stream, pipe and asynchronous code. So, if you are familiar with Node.js you will love Gulp. Gulp is relatively new and can be seen as a rival to Grunt. But its code driven nature makes it unique. As more and more projects are adopting Gulp, this is going to be the go to build system in near future, IMHO.