Gestures on trackpad for recent (libinput) Linux. It runs xdotool to stuff the keyboard buffer with keystrokes when it sees certain gestures. E.g. three finger swipe left and right do Alt-Left and Alt-Right, which have the effect of Back and Forward in the browser and some other browsing apps (e.g. IntelliJ). Four-finger swipe left and right switches desktop on my machine. It's one more finger than Mac but probably required not to conflict with two finger scroll.
Continuous: pinch zoom, rotate, swipe between pages, swipe between virtual desktops, swipe between fullscreen apps, show notification center, show all windows on current desktop ("Mission Control"), show all application windows ("App Exposé"), show Launchpad, show desktop
Discrete: browser back/forward I guess?