I always put the same example, but it's because I think that if you have to learn something from someone, is better doing it from the best or at least from the leader, Google Chrome for me.

Here is there user experience once again. Now, we can see it in error messages, a new way to communicate to users beyond the system state status information.

So, what is the lesson learned? the face is personalizing a web browser not a user, because it is not a user mistake but a system one. Obviously, the art pixel contributes to catch the attention... well, don't get confused, main reason is it's strongly cool :) like my smiley.