I love little things like this. It seems silly, but goals have been proven to motivate people. They don’t work alone, but when combined with other compelling expereinces goals can put your user’s average time on site through the roof.  A recent example of this is what you see in Linked in. 

I hate managing both linked in and Facbook, but I still log in every now and then.  I don’t want to stay, but hey, adding a picture gets me to 80%!