I think I linked to Erin McKean's excellent 2006 post “You Don't Have to Be Pretty” at some point, but I can't find the link, so I figured I might as well repost it somewhere where I'll be able to find it again.
A particular paragraph of that post has been making the rounds, but it's being misattributed. As quoted in a bunch of places, it's attributed to Diana Vreeland; Vreeland's photo is at the top of the post, and McKean mentions Vreeland by name near the end, but Vreeland didn't write it.
The misattributed paragraph:
You Don't Have to Be Pretty. You don't owe prettiness to anyone. Not to your boyfriend/spouse/partner, not to your co-workers, especially not to random men on the street. You don't owe it to your mother, you don't owe it to your children, you don't owe it to civilization in general. Prettiness is not a rent you pay for occupying a space marked “female.”
The whole post is very much worth reading. Another line I liked: “I was going to make a handy prettiness decision tree, but pretty much the end of every branch was a bubble that said 'tell complainers to go to hell' so it wasn't much of a tool.”