Like it was said earlier, a tractor its self is awesome. But as for the implement 'must have' list....
Loader would be the first must have, after not having one for to long until the 790 came along with a loader. Knew I could use one, but found more uses than originally thought of after owning one.
Second, its the box blade. With a box blade you can rough up a spot darn near good enough for a garden, fix a driveway or build one, level land, slope and shape land, remove brush, roots, trees, plow snow or just used as ballast. Its really hard to beat the utility of the box blade. Its the item I wish I had bought years ago...
The tiller is the other implement that seems to hang of the back of the tractor a good while also.
Rear blade, It is a main stay item from somewhere in late November till around the first of March.