I came across this handy tip a few days ago, and thought I’d post it for any other Mac users out there. :)

Launch the terminal and type the following command:

defaults write com.apple.dock persistent-others -array-add '{ "tile-data" = { "list-type" = 1; }; "tile-type" = "recents-tile"; }'

Then you’ll have to restart the Dock by issuing the following command:

killall Dock

The Dock will disappear for a moment then reappear. Your Dock will have a Recent Applications Stack located to the left of the Trash icon.

If you ever want to get rid the stack, just drag it off the Dock and it will no longer show up.