I tried to post this twice today and both times I lost it :( So now I'm doing it for the last time. Good thing it is a short recipe! Here is an icy treat that I made for me and my diet buddy on our first round. It's sure to satisfy you on a hot day.
Iced Mocha
2 Cups brewed coffee (chilled)
1 Tablespoon Milk
3-6 Drops Dark Chocolate Stevia
3-6 Drops Hazelnut Cream Stevia

1. Mix all together and taste. Add more stevia if needed.
2. Pour in a shallow dish (freezer safe) and place in freezer uncovered. 
3. Flake with a fork every 15-20 minutes until entire dish is in a consistently slushy state.

This makes more than enough for 2 servings and the only calories in it are from the milk (~5 calories). It can be done without the milk, if course.
You can use this method with your favorite tea and you can even take it a step further. Try adding your allowed fruit to the tea and spin it through your blender. (I'll probably freeze my fruit first to speed up the process.) 
Enjoy!
Cheers :)
CAT