Water Joe

Unbelievably obvious from a marketing point of view: spring water with caffeine, nothing else. Equivalent to a can of soda or a cup of coffee. Available in the Midwest and Southeast US, but probably not a lot of other areas, although I'm surprised it's not more popular!
I haven't tasted it yet but supposedly it just tastes like water, the caffeine is subtle. I just heard about this from the guy sitting behind me in my statistics class, and I'm posting this from class... :)