I love the slushies, but could do without the sugar and calories
Here in AZ, a place called QT(convenience market-gas station chain) usually carries all kinds of slurpee/slushies--even the diet ones made by Crystal Light. At home, and when I'm in Playa, I throw about 2 cups of ice and 1 cup of whatever diet (or not diet) drink into a blender at "puree speed" and it turns out great (never tried it with a soda, though...)! Makes all kinds of flavors--just don't use any real fruit because then the texture is all wrong and it becomes a smoothie.
BTW--I could swear I've gotten a regular slurpee at the 7-11 in Mexico.