Whodathunkit? Check out My Cup Runneth Over for the idea and how-to's. i think i will show this to dh when he gets home.
I think this might be on the agenda for next year's garden.
I do remember playing in the backyard of my Great-Granny's house when i was a kid and she had a huge tractor tire back there. I wonder if that is what she used it for, back when her health was better?