If you're using Firefox, just right click on any links nearby and you should see 'Send Link...' in the context menu. Clicking this item will open default email client composition window with this URL, type your friend's address and the link will be ready to be sent. Now you know what I'm gonna talk about.
It's one of features I've never used since my first browsing experience with good old Netscape 3.0 Gold. It's also one of my most-hatred features because I always misclick it and end up with waiting Thunderbird to start.