Garbage Disposal
This is the most compact design (3x3x3) for a garbage disposal I've been able to come up with while retaining the ability to easily cover it up, like burying it so just the chest is visible.
The glass is just to show you how the lava was placed. There is a bug that I've run across when you dispense items directly into a lava block where sometimes the lava block will get destroyed. You can solve this by placing a lava block directly below the dispenser and a lava block adjacent to the first lava block. Another way is to leave an empty block between the dispenser and the lava block, but that means you have to dig down one more block making this 3x3x4.
