lifehacker has a neat tip in this post today: Quickly Copy a Website URL into an Email with Cmd+Shift+I on Mac.
I use this tip all the time, but I don't use the keyboard command.
I just go to the menu:
FILE > Mail Link to this page
Image: File Menu item Mail Link to this page 'Shift+CMD+I'
The correct designation of the shortcut, as displayed in the menu item is, Shift+CMD+I.