ZURB's Foundation is a front-end for quickly building applications and prototypes. It is similar to Twitter Bootstrap but uses Sass instead of LESS. Here you will learn the basics of the grid system, navigation, tooltips and more.
AngularJS is an awesome framework for easily creating rich, client-side applications. Its powerful bindings allow you to do a lot with very little code. Here I show how to integrate Angular with a Rails app.
PostgreSQL Schemas can help create a multi-tenant app by keeping data separate at the database layer. Integrating with migrations can be tricky though, so watch this episode for the full details.