I'm hoping that the new pyramid temple thing will bring with it a new mob: Mummies. They could come from spawners that generate with the temple, much like blazes only spawn from spawners in nether fortresses. Also, loot chests need to have more valuable items than just iron, gold and whatnot, they should have a chance of containing enchanted items and potions.
Ack, that reminds me of the week or so I spent playing on a public server back in alpha.
Every day I'd log in to find my house griefed in an inventive new way.