Have rubbish removed. Reticulation laid Prune or remove trees. Retain a wall. Lay a concrete slab, or a concrete path. Install some garden lights. Top soil dress. Clean up that mango mess. Fill in a pool or build one. Build a fence or have the existing fence repaired and painted. Lets do a sand pit or a playground. While your at it do your front yard as well. Put up a shed A water feature or a fish pond. YOUR IDEAS ARE ONLY CONFINED BY YOUR BOUNDARIES