I'm probably wrong, so do NOT trust my word 100%, but i believe there's a new skin system working, where you can keep the heads of what your skin WAS.
So for instance, if you need a security camera head or a hamburger head for decoration, like the ones I use at my zoo, instead of keeping your skin that all the time forever, and having ALL your heads look like that, you can change your skin to a hamburger, collect a bunch of heads, and then switch back to your normal head, and it will stay a hamburger. Any heads collected each skin change, will reflect that new skin change
For example, the command USED to be something along the lines of "/give boysandghouls playerskull [name]" or something. NOW the command looks like this:
"/give @p skull 1 3 {SkullOwner:{Id:59ad9020-d6eb-11e3-9de4-1a514932ac01,Properties:{textures:[{Value:eyJ0ZXh0dXJlcyI6eyJTS0lOIjp7InVybCI6Imh0dHBzOi8vaS5pbWd1ci5jb20vS1Fua2sxcC5wbmcifX19}]}}}"
which would give you a miniature first-aid kit head \ o /
Again though, I'm not sure if this is implemented yet, or part of 1.7.9. I could be 100000% wrong, so until an admin confirms/denies what i just said, take it with a grain of salt
