The heads on heads.freshcoal.com are not player based. They do have an UUID but it is not connected to any player. If you would decode the command it gives you then you will see they get the skins texture from the minecraft skinservers.
(These are heads that do use usernames:) MHF_ArrowDown MHF_ArrowUp MHF_ArrowLeft MHF_ArrowRight MHF_Exclamation MHF_Question
If you google Marc's head format you will find more of them.
You are all wrong, the hotpage at projects is indeed broken/frozen. You can see the real hot projects at the slideshow when you first click the projects tab. Now the same projects have been on the frozen hotpage for over 11 days. I am not posting anything new because it will not show up on the hot page. Im not saying all the projects on the hotpage dont deserve to be there but it isnt fair for the other projects.