What follows is are the recipes for all the skulls
If the config more_difficult_to_obtain_heads is true, a player head is crafted from 9 wither skulls.
If it's false, a player head is smelted from a wither skull.

SethBling's head:
redstone redstone
comparator redstone
torch head

CavemanFilms's head:
Shapeless, a bone, a stone pickaxe, a head, and a rotten flesh

SkyDoesMinecraft's head:
Shapeless, a head, a butter nugget, a butter ingot, a butter block, a butter hoe, a butter sword, a butter chestplate, a butter carrot, and a butter apple (from the blocks, not the ingots).
Bashur's head:
melon melonblock melon
melonblock skull melonblock
melon melonblock melon

Deadlox's head:
Shapeless, a head, a potato, a brown mushroom, and an ink sack.

Dinnerbone's head:
Shapeless, a bone, a dropper, a head, and a nametag.

Jeb's head:
tallgrass head tallgrass
enchantedbook emeraldblock enchantedbook
emeraldblock emeraldblock emeraldblock
(think enchanting table!)

Notch's head:
grassblock head grassblock (you need silk touch for this one)
enchantedbook diamondblock enchantedbook
diamondblock diamondblock diamondblock

Herobrine's head:
head head head
head witherskeletonskull head
head head head

Creeper head: (can't be recycled)
Gunpowder sand gunpowder
sand head sand
gunpowder sand gunpowder

Skeleton head:
___ head ___
bone bone bow
___ head ___

Spider head:
Shapeless, 2 spider eyes,  a head, 1 string

Zombie head:
flesh flesh flesh
potato head carrot
potato ironingot carrot

Slime head:
Shapeless, 1 head, 3 slimeballs

Zombie pigman head:
Shapeless, 1 head, 1 rotten flesh, 1 butter sword, 1 butter nugget

Ghast head:
Shapeless, 1 gunpowder, 1 head, 2 ghast tears

Enderman head:
Shapeless, 1 head, 1 ender eye, 2 ender pearls

Cave spider:
Shapeless, 1 head, 2 fermented spider eyes, 1 string

Blaze:
___ head ___
blazerod firecharge blazerod

Magma cube:
Shapeless, 3 magma cream, 1 head

Wither:
___ witherskeletonskull ___
___ beacon ___
diamondblock diamondblock diamondblock (for the beacon to work xD)

Pig:
grilledpork pork grilledpork
pork head pork
grilledpork pork grilledpork

Sheep:
redwool orangewool yellowwool
blackwool head greenwool
brownwool purplewool bluewool

Cow:
cookedsteak steak cookedsteak
steak head steak
cookedsteak steak cookedsteak

Chicken:
egg feather egg
feather head feather
egg feather egg

Squid:
inksac inksac inksac
inksac head inksac
inksac inksac inksac

Mooshroom:
redmushroom steak brownmushroom
cookedsteak head cookedsteak
brownmushroom steak redmushroom

Ocelot:
If you use the new recipe:
cookedfish fish cookedsalmon
clownfish head salmon
cookedsalmon pufferfish cookedfish
Otherwise:
cookedfish fish cookedfish
fish head fish
cookedfish fish cookedfish

Iron golem: (obvious)
___ head ___
ironblock ironblock ironblock
___ ironblock ___

Villager:
Head
Leatherchestplate
Leatherpants

Chest:
planks planks planks
planks head planks
planks planks planks

Cactus:
cactusgreen cactusgreen cactusgreen
cactusgreen head cactusgreen
cactusgreen cactusgreen cactusgreen

Oak Log:
___ planks ___
planks head planks
___ planks ___

Melon:
slice slice slice
slice head slice
slice slice slice

Cake:
milk milk milk
sugar head sugar
wheat wheat wheat