So much urban mythology is built around caffeine. Is it good for you or bad for you? Which has more caffeine, Coke or tea? Can you die from drinking too much Red Bull?
Finally, a site devoted to caffeine. It's called Energy Fiend. On it you can find a list of every conceivable caffeinated drink, and the amount of caffeine in it.
You can also find a useless little calculator that will tell you, based on your body weight, how much of your favorite caffeinated beverage it will take to kill you.
It also has a list of common energy drink ingredients and their function. Ever wondered what guarana was supposed to do for you? Wonder no longer.