Odwalla and Arden's Garden make smoothies with veggies - they have names like "SuperGreens." (I don't like Bolthouse Farms.) I usually water it down a little and served it iced in a sippy cup with a straw because it looks pretty dark and thick and not very appetizing. Although after a while my kids got used to it and they have no issue at all slurping down a thick dark green liquid. (It's very sweet, I think they use lots of apple juice for the base.)
Most produce sections will have a big selection of smoothies. My kids like the Brazilian ones made with acai - (don't worry they won't lose weight, and they are delicious.) Pre-made smoothies can get expensive, though, so you may want to blend up some of your own.
Fruit smoothies *are* healthy, though - no need to try to turn it into soup. (And actually, a hanful of frozen blueberries or plain yogurt is gonna be a lot healthier than chicken broth.)
I always have bananas in the house, and whenever they some start to get over-ripe, I peel them and put them in a ziplock and throw it in the freezer. (Almost all of my smoothies start with frozen banana. It gives it a lot of sweetness.) Add milk and/or plain yogurt. More frozen or fresh fruit (strawberry and blueberry are popular.) And maybe a scoop of whey or protein powder. (The chocolate ones don't taste very chocolatey to me, so I sometimes add a little extra cocoa.) Trader Joe's makes a soybean powder that has almost no flavor but adds lots of protein. Or you can also add silken tofu, but you need to use it up within a few days. The kids won't drink it if it's not sweet enough, so add a bit of honey or sugar, but you shouldn't need much.
And Dr. Sears has a recipe for a breaskfast smoothie he calls "School-Ade" http://www.askdrsears.com/html/4/T040401.asp
My kids have liked these combinations:
For all of them, I start with a frozen banana, a big dollop of plain yogurt and milk. Then try one of these combinations:
(1)strawberry, vanilla protein powder, possibly honey
(2 blueberry, chocolate protein powder and cocoa (They LOVE the combination of cocoa and blueberries, and the fruits naturally sweeten it.)
(3)peanut butter, chocolate protein powder and cocoa
ALWAYS do a taste test to see if it needs extra sweetening before serving or you'll end up throwing it down the drain.