Email Friends feature
Is there a feature that allows users to enter email addresses for friends and that will then send an email to those addresses? (By friends, I mean anyone, not just friends they've "linked to" through the friends plugin.) This would seem to be a key feature of a social application. Just having a button on a page that a user clicks to initiate this function would be okay, but what I'm looking for is something that when a user saves an edit or post, or in some way contributes to the website, that a message will pop up asking if they would like to share what they just did with their friends.
Does such a feature exist?