Schools, universities and churches have big lawns here in DC, they could definitely use some sheep or goats to do the lawn. It would also have a great impact on raising awarness on sustainable issues. And the manure could be use for the composts of community gardens which seriously lack this type of material.
I wanted to find a similar company to rent ducks to get rid of some bugs in my community garden (and to get manure), but I haven't found one in DC itself... There is definitely a great opportunity for companies in this field!