Hopper Furnace

The hopper furnace is actually a fairly simple concept. All it really does is cook/smelt things semi-automatcally. You hook up chests and hoppers leading to corresponding places on the furnace.

The chest on the left contains fuel (I used blocks of coal), the one on the top contains cookable/smeltable items (raw meat, ores, etc.), and the one on the bottom has the cooked items.

This can be useful when you don't want to keep changing what you want to smelt only to find an occupied furnace. Sure, you could just make another one, but this one is pretty charming.