LaTeXit: For high quality equations and Feynman diagrams to put in Keynote presentations.
Keynote: My favorite tool for creating presentations. Easily handles vector graphics, has nice suggested gridlines to snap to so that your visuals are nice and symmetric, super easy to use, nice transitions for those presentations when you don’t have to go back through slides, export to PDF for when you have to upload your presentations beforehand on to windows computers, and oh, did I mention vector graphics?
Homebrew - The package manager I use to keep everything working and linked properly on my Mac.
Evernote: Great for jotting down notes quickly. (And daily agendas, for those days when Omnifocus seems a bit overwhelming, and also when I want to have a sequential list of tasks to do - Omnifocus doesn’t allow me to manually drag and change the order of tasks.)