A Gold Nugget is an item in Minecraft. It is made by putting a Gold Ingot into a crafting grid, which breaks down to 9 nuggets. Also, placing 9 nuggets in a 3x3 grid will make an ingot. Gold Nuggets can be added to make Glistering Melon, an ingredient for potion making. They are dropped by Zombie Pigmen when killed. They have no uses other than being used to craft glistening melons, golden carrots or golden apples.
Filling the Crafting Table with Gold Nuggets will restore the Gold Ingot used to create them.
Surrounding an Apple with eight Gold Nuggets will create the rare Golden Apple, which will instantly heal four hearts when eaten regardless of hunger level.
In some multiplayer servers, they are either traded or used as currency.
On some servers without a money system, Gold is used as a currency as 81 nuggets = 9 ingots = 1 gold block allowing for goods to be purchased.
Since Zombie Pigmen carry golden swords with them, it is likely that the gold nuggets are pieces from the destroyed swords since they are not dropped upon death. Only 1/18th of the gold from pigmen's swords are salvaged (assuming 100% drop rate). As of 12w06a, the swords themselves are rarely dropped.
With the addition of the gold nugget, gold has become a renewable resource, adding the metal block, the third tier of armor, the third tier of tools, the golden apple (since red apples are renewable as of the prerelease 11w48a), and the Glistering Melon to the Renewable Resources list.
One would need 216 gold nuggets to craft a full set of gold armor.