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.
Pondless Backyard Fountain Pond and Waterfall. Even without the fountain, which in Az will grow algae like nobody's business, I think the idea of softening up the patio with a little rock garden with plants mixed in.