It's kind of an indexing multi-purpose launcher you hit the hotkey, and type something, and it gives you choices. There's no real equivalent on Windows, but I couldn't live without it now. It watches all your network traffic, and gives you the ability to stop any of it - like, extraneous or excessive phone-home behavior from Microsoft apps. If you're an open-source person, there are native builds of both emacs and vim available.
Sublime Text is probably the leader right now, but some folks like BBEdit (which is paid). A good text editor, if you need that sort of thing.Fantastical, if your calendaring needs are beyond what the build-in Calendar can do.Here's a few things I absolutely require, though, plus some tips on what you do NOT need. Most of what comes with it is really pretty solid.
