The Elusive Spider Jockey
One of the rarest mobs in Minecraft, it's a skeleton that rides a spider. Every skeleton has a 1% chance of spawning as one of these.
Fishing For Enderman
It's possible to hook an Enderman with a fishing rod; if you do this while they are neutral they will stay neutral.
Roses are more rare than dandelions.
If a skeleton kills a creeper with an arrow the creeper will drop a music disc, which can be played.
If lightening hits a creeper it will become 10 times more powerful, the explosion will be massive.
Creepers and Skeletons will not see or attack players through glass.
Cobwebs will slow down a creepers explosion timer if they are caught in it.
If you are above or below a skeleton, he will end up shooting himself.
On Halloween all the mobs will sometimes wear Jack O Lanterns or pumpkins on their heads.
Cave spiders can poison skeletons, however the skeletons will not die, as he will only have half a heart left.