Kamyu's tools is a set of tools that allows map makers many highly configurable options to assist in the creation of their maps. These tools make random loot chests, custom potions, and custom mob spawners for use in MCedit and Minecraft.
Custom Spawners and Populate Chests are both confirmed. Potion Chest is likely used to make potions such as the jump boost potions that are spawned in Salire Castle. Custom Shops will be used in special NPC villages in an upcoming map, but have not yet been used.