In Mac OS 10.8 Mountain Lion, Apple removed the Email link to this page option in Safari, replacing it with Share > Email this page, which places the entire contents of the page into the email, images and all.
Sometimes this isn't what you want, though. Sometimes just a link is best.
I've written a short AppleScript to perform the old "just a link" function, and will explain how to make it run from within Safari using a customisable key command.
Actually, funny story. While messing around, I discovered an undocumented keyboard shortcut which does this. It's ⇧⌘I. This completely obviates the need for the script I wrote, but I'll keep the instructions here, incase reading about moving data between Safari and Mail using AppleScript is something you'd find useful.