What is a satisfying [read, not water substitute for diet soda pop?

Recently I had the intestinal flu and drinking pop made me feel queasy, so I stopped drinking it. I’ve been without now (caffeinated and non) for about a week, no ill effects.

The problem is, in the interim, I’ve been drinking fruit juice, whole milk and soy milk. Healthy enough, but relatively expensive and loaded with calories. Yes, I’ve had plenty of plain tap water as well… my limit.

Any tips or suggestions for a satisfying substitute for pop? Something maybe slightly sweet-tasting, or with more ‘body’ than plain water?

I know it’s the New Year and there are others out there trying similar experiments. Can you help us out?