First, I'll say that you should take the time to get to know the features of the OS, before running out and getting a bunch of 3rd party utilities. In terms of built in stuff you may or may not already know about if coming from another platform... - Spotlight: (⌘space) launch apps, universal search, basic calculator, etc - QuickLook: (space when a file is selected in Finder, space again to close it) Preview a wide va…
took me only a day to forget i ever used apple+space for apps (though for non cli apps i still open finder to app-window to find some obscure thing in Applications ive forgotten names of)