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.
Simple potting bench or gardener's station. This sturdy, easy to build design will bring potting plants to counter height, and can take the place of an outdoor bar come summer BBQ season. Paint a bold color to update the look and styling.