Is that just a thing with a dropdown of a lot of moods, and then in your skin display a big smily face for whatever mood you are in?

Thats the one!

Pretty darn easy, maybe a hour job for someone with some skills, or maybe a days job for someone without.

If you want to try, look at GetDefaultUserSettings, stick in a dropdown with the values being that of all the moods, add a moods directory to the media folder, and stick in the images there, then make a function like get_mood_url($mood) which will get the image url for your mood, and then stick in a call in your skin.

I have absolutely no time at the moment for anything, but anyone with some curiosity should be able to knock it off in no time.