I recently caught a screening of the movie "A Convenient Truth: Urban Solutions from Curitiba" and although I was familiar with their public transit system, I was intrigued by a program I didn't know about that they have there which uses sheep to keep park grass cut.
The sheep move from park to park grazing the grass which saves on the need for lawnmowers. The sheep are tended by a shepherd who works for the city. From what I have read elsewhere, they also are able to make use of the wool the sheep produce.
I realize that zoning might be a problem in North American cities to allow livestock within city limits, but I like the idea. Has anyone tried this in other cities?