Here are all of the things I swear by or simply believe deserve a link:
Atom.io – The most awesome hackable IDE for any lang
Deco – An Awesome IDE for React-Native
FreeMind – A great application for creating flow layouts for apps before you start programming
Crouton – The beautiful script to turn your Chromebook into a great development system by adding Linux to it
Linode – My goto solution for server hosting, because I prefer to do it “my way”; Linux and BSD support.