Does a small Frappuccino give you enough caffeine to be worth the calories? How long would you have to run to work off an iced latte?
David McCandless' awesome chart puts all of your caffeine concerns in perspective. The chart, posted on his Information is Beautiful blog, puts caffeine on an X axis and calories on the Y, plotting the majority of drinks one can brew at home or shell out spare cash for all around the grid with representative sizes. This allows you to find your personal energy beverage sweet spot -- say, 150 calories and lots of caffeine or almost no calories and just a soda's worth of the temporary boost -- and see the caloric equivalent in food, alcohol, or 30 minutes of exercise.
I did learn from this chart that black tea is better than 2 painkillers, and that if I consumed an "ultra coke" I would need to roller skate for 30 minutes. So, what's that morning cup worth to ya? Check out the complete the Buzz vs. the Bulge chart.