The current “Tip of the Week” from Apple describes 
how to email a URL from Safari.
It’s as easy as pressing ⇧⌘I and then sitting back while Mail.app creates a new message containing the link.
That’s it.
I hesitated about posting this, but sometimes tips aren’t as well known as you might think, like using ⌘] and ⌘[ to cycle through the available HTML, Rich Text and plain text views of an email, or using Gmail-like “Conversation” views in Apple Mail.
If you use some other browser, you will have to make your own arrangements. OminWeb users can use a bookmarklet to send a link, Firefox users can customise their toolbar by adding a “Send Link” button and Camino users can uses ⇧⌘L.
