Since I have been here I haven't been able to see a "currently active users" list, but in my user CP I have the option of being invisible so I don't get put on the active list.
So can anyone tell me where I can find it?
Warrior, the little egg icon on the bottom left, below your avatar, shows if you are online or not. The egg will have a yolk if you are. If you choose invisible, your egg will always be solid white so no one will know if you are online.