I supplemented my diet with juice, both as a way to add more variety of nutrients and because frankly, I was getting kindof sick of all of the Boost/Ensure and milkshakes I had to eat. Lots of things you can add to milkshakes to make them more interesting and give a greater variety, but I was craving things that were NOT high in fat and dairy. That being said, as you have heard above, there are not many calories in a juice.
Every couple of days for awhile I had a juice of some sort. Generally speaking, I'd add kale, celery, cucumber, carrots and either an apple or a pear. I'd vary it with beets, ginger, lemon, or substitute spinach for the kale. It's somewhat of a pain in the butt to have to wash and cut up all those fruits and veggies. To make the washing process somewhat easier, I'd mix up some water and some vinegar in a large bowl and wash a few days worth of veggies at once.
Now that I can eat solid food again, I juice less often, but still use it as a way to add some extra vegetables into my diet whenever I feel I haven't been getting enough lately.