Grow an Avocado Tree from the pit (for a houseplant, it probably won't produce fruit). After drying, the pit is suspended in a glass of water and once there is root growth of about 2″, it can be planted in a pot of soil and tended to as a houseplant. If your climate allows, you can plant this outdoors.
Bonsaï forest - it is cute, it is small, it has just a few trees; yet it is a stunning arrangement with well trained trees. Put your hand over the pot and you would not be able to tell whether this is a picture of natural trees or a stand of Bonsai trees. Nice design and fantastic execution,