While CMD-clicking a link opens into it into a new tab, there’s more to this modifier key in Safari.
CMD-click a Submit button in web forms to open the resulting page in a new tab - this keeps your painstakingly filled form intact.
CMD-click the Back button to open the previous page in a new tab. CMD-Enter a URI in the address bar to quickly open new tabs with that address, and (my favorite) CMD-Enter a Google search in the window top to open the results in, yes, a new tab.
