True Lemon/True Lime
We were hesitant to try these little packets. We stared at the boxes for a few days. We finally tried them out in water and in some tea, and we were surprised—shocked really—at how impressive they were. Made from lemon or lime juice and lemon/lime oil (and not much else) these lemon/lime "substitutes" do a pretty good job of flavoring up your favorite drinks. They are all natural, have no calories, and provide 25% of your daily recommended Vitamin C. Simply add a packet to a bottle of water and voila, you have instantly flavored, tangy, refreshing lemon (or lime) water (or soda or whatever). Perfect for the gym or for on the go. They can also be used in cooking, but we're pretty happy with the real thing there.
The True Lemon site has links to online vendors, a store locator, and even offers a sample box for free.