Minecraft wiki entry for Farming, associated text: Cactus farming
Farming cacti for green dye or traps.
Cobblestone farming
Creating a stone or cobblestone generator for self-repairing shelters or harvesting.
Obsidian farming
Creating an obsidian generator for obsidian-intensive builds.
Ice farming
Farming ice using a self-refilling rink.
Tree farming
Farming trees for wood, saplings, apples, or charcoal.
Wool farming
Farming wool for many different uses