2. Press "t" then type "/gamemode 0" without the quotation marks. "/gamemode 1" will bring you back to creative mode.
This works fine, if you're creating a new world and with cheats enabled. If you have an already-existing world you'd like to switch over, and upgrade to 1.3, it will not have them enabled and then you'll need a mod like Too Many Items.
Village Mechanics: A not-so-brief guide - Update for 1.4! Added subsection on iron farming to the iron golems section. Only ten villagers required to spawn golems (down from sixteen)! Put to rest the "facing doors cancel each other" myth!