It really pays to read labels - I just read the label for the soft drink Fresca --- the can does not mention that it is a "diet" soda.
FRESCA is calorie and caffiene free !
Which means you can count towards your daily water needs.
For those of you who have not tried one, it is a citrus-y lightly carbonated soda with a grapefriut flavor. I really like it as an alternate to diet 7Up or Sprite. It is made by Coca Cola and I can usually find it on the supermarket.
But it does have aspartame so those of you who try to avoid artificial sweetners are out of luck.