One of the tools in our SPA toolkit is underscore.js.  It was a new tool that I fell in love with instantly.  It really helps to make javascript code simpler, cleaner, easier to read, and more maintainable. Here is a list of links for learning and reference.

General Knowledge

underscorejs.org
GitHub: Underscore.js
StackOverflow: About underscore.js

Videos

Pluralsight: Underscore.js Fundamentals

Blog Posts

An Introduction to Underscore.js by Dan Wellman
Eloquent JavaScript with Underscore.js by Something Somewhere.
Easy functional programming in JavaScript with Underscore.js — part 1 by Nick Morgan :: Part 2

Books

This book is going on my “to read” list for JavaScript.  I read through the introduction and it appears to have some great information about JavaScript functional programming as well as being a good example of how to utilize underscore.js. Anything with good code samples is key in my world.