Farm animals that are work animals

I'd like to do more with the animals we are allowed to do things with.

I'd like to make carts for horses (perhaps a combination of lead, minecarts and boats in the craft box?) that can pull the player and a chest.

I'd like to see some farming and construction equipment that puts cows to a use besides slaughtering them for meat and leather. Perhaps a "grader" or "plow" cart that uses up picks and shovels to tear up dirt and stone 1-2 meters above the level you are on (faster than the player is capable of), and lays dirt -or whatever block you have placed inside it- on the level below you to fill in gaps in the ground for your expanding base/city.

I'd like to be able to set an item down (or carry an item) that tells dogs to herd sheep and cows that are within X range (and keep them within X range) so they won't run off while I'm building fences.