Designing your own vertical herb garden is a fun project. Vertical gardens allow you to grow herbs and some fruits and vegetables that do not require a lot of soil, such as strawberries or lettuce. Growing your own herbs for cooking or for medicinal.
DIY - Homemade Gabion wall ie rocks encased in wire baskets and used as a retaining wall - creates a dramatic feature in a garden. No directions on link. Nice someone figured out how to landscape with river rock. I swear they grow!
Reuse an old tree to make a log pathway in your garden. Good use of "yard" trees and other wood that can't be milled; works much better in climates without termites. Good drainage under the log rounds will make the path last longer.