Jarrah railway sleepers are fairly cheap for their size, and would make great raised beds. I'm thinking of using them to create a terraced vegetable plot, with the espaliered fruit-trees at one end against the wall.
(herb garden idea) Got Pallets? Don't feel like turning up a bunch of grass? Use a pallet as a garden bed - staple garden cloth on the backside of the pallet fill with dirt and start growing! Courtesy of: Backyard Diva