Front-end topics

JavaScript Design Patterns
Node.js - Streams / Scaling / Microservices / Etc
Phonegap
ClojureScript / OM (Lisp on Client)
PureScript or Elm (Pure Functional Languages)
Client-Side APIs (Amazon, Facebook, Twitter, etc)
Flux Application Architecture / Redux
Relay / GraphQL or Falcor
Build an app with pure ES6/7/'15/'16
Rendering Performance (Hardware Accel, Painting, etc)
Offline APIs / Web Workers / Service Workers / Local Storage
Security
Polymer / Web Components
RWD Performance / Progressive Enhancement
Dev Tools - Network, Performance, HTTP2, etc
UI design / Mobile design patterns / Data driven design
CSS preprocessors LESS/Sass/compass/stylus
Accessibility
CSS frameworks - Foundation / Bootstrap
Hybrid applications / Ionic / Electron / Nw.js
Three.js / WebGL libraries
Databases - MongoDB / Rethink / LevelDB / CouchDB
JavaScript on Hardware (Arduino/etc)
A/B testing / Analytics
How browser work - WebKit/Blink internals
Diagramming / UML / code explanations
More Ember 2.x
More React.js / Advanced
Angular 2.x
More Unit Testing
Web Animation
CS101 / Algorithms & Data Structures
Creating Open Source Libraries
Webpack
More Pure JavaScript Deep Dives (ES6/7/'15/'16)
More Reactive Extensions (Rx.js / Cycle.js)
Creative Coding / Processing, p5
More Data Visualization / D3.js