If you seek out coffee merely for the caffeine, you might be interested in a new iPad/iPhone app called ‘Caffeine Zone‘. After setting up the app, you tell it when you consume caffeine, and it plots out a graph showing the caffeine level in your body over the next 24 hours. This will help you see when you’ll feel the sleepiest, the most active, etc. Useful as an educational experiment, in the day to day life, I think serious coffee drinkers eventually learn this on their own. They know how late they can drink coffee and still get a good night’s sleep. They know if they’re feeling tired. Etc.