Sublime - http://www.sublimetext.com/
A text editor many devs at Jam3 use because it's lightweight and has many plugins for added functionality.
Package Control - https://packagecontrol.io/
Install and manage plugins for Sublime. (must have)
Checks your javascript files for potential errors.
JSONLint - https://bitbucket.org/hmml/jsonlint
Checks your JSON files for potential errors.
Helps you write js doc documentation in your Javascript files.
Gives you code higlighting for Less files.
Handlebars - https://github.com/daaain/Handlebars/
Gives you code highlighting for Handlebars files.
A dev server for rapid prototyping
Run tap based tests in multiple browsers. Autoreloads when a Javascript file has been changed. Distributed through npm.
nodemon - https://www.npmjs.com/package/nodemon
Run a Javascript file in the commandline. If a Javascript file changes nodemon will restart the process.
internal-ip - https://www.npmjs.com/package/internal-ip
Get's your internal ip address quickly for local testing. Distributed through npm.