Vagrant - Allows you to create lightweight, reproducible, and portable development environments. So each new developer on your team can be up and running in 10 minutes. Gone are the days of spending a day or two setting up your dev environment. An even bigger benefit is having the exact same setup as production, so there are no gotchas when deploying (missing components on production, etc).
Chef - Server provisioning. It has a steep learning curve, but saves us hundreds of hours a year for provisioning new servers. Vagrant supports Chef recipes as well. Alternatives are Puppet and Sprinkle. If you have a very small setup, use Sprinkle. Both Chef and Puppet are overkill for smaller architectures.
Navicat - Some free alternatives like Sequel Pro might come close, but Navicat has some key features that take away a lot of time consuming tasks. It has automated backups, support for all the popular DBs (Sequel Pro is just MySQL at the moment).
Sublime Text - GitHub's Atom might take the crown down the line, but Sublime Text is the best editor at the moment. If you prefer a full-fledged IDE, RubyMine is the gold standard for Rails.
Fish - Once you give Fish a try, you'll be confused as to why you were using Bash or Zsh as your shell all these years. Zsh could be customized with Oh My Zsh for a similar setup, but would still miss some nifty time savers that Fish has. Note: For writing shell scripts, it's probably better to stick to Bash since every linux distro will already have it installed by default.
Bohemian Sketch - After years of using Photoshop, switching to Fireworks was a breath of fresh air, as it was the better tool for the job. But then Adobe decided to kill Fireworks. Sketch is the closest thing to Adobe Fireworks, and then some.