I often do the frozen fruit thing, too. I like to put mangoes, blackberries, bananas, and strawberries in there with some yogurt. Sometimes add a few ounces of red zinger or pomegranate tea to loosen it up a bit. I usually crack open a couple of echinacea caplets as well.

Other things that work well:
kiwi (not too much)
raspberries
blueberries
huckleberries
peaches
mint leaves
protein powder
juices

Deelish. Anytime I have a hankering for a milkshake, I just make a smoothie. It's so much healthier but works just as good.