Look at this perfect tool rack organization. It was made from new wood in the link where we found it, but could easily be made out of pallets or with Rust-Oleum wood stain!
DIY Garden Tool Organizer : upcycle a wooden palette by hanging onto the wall of shed or garage to store garden tools (Lowe's Creative Ideas Pallet Project).
Pallets hay feeder in pallet garden pallet outdoor project with Pallets Farm DIY Pallet Ideas
Make a Pallet Fence that will cost you nothing. (Maybe to fence off a garden area)