Relating to both the original post and pianowelsh's previous post on coffee:
If you want something that will stimulate your mind, try drinking green tea. I was an avid coffee drinker until about a year ago, when a friend of mine turned me onto Yerba Mate (a member of the green tea family, from South America). I've been drinking it ever since, and I don't miss coffee the slightest bit.
See, coffee is like crack. It gives you quick jolt, and then about an hour later, you totally crash, and you need to keep guzzling coffee all day. Coffee also gives you a nervous type of energy (jittery feeling).
Not only is Mate much healthier than coffee (it contains nutrients and antioxidents), but its much, much easier on your system. It contains "mateine", which is chemically similar to caffeine, but is slower acting and longer lasting. It doesn't give you the immediate buzz of coffee, but I think it gives you more overall energy. It's "relaxed" energy, meaning that you won't feel jittery and "cracked out" like with coffee. It's also longer lasting and slower to wear off, so it doesn't have the drop-off, or "crash" effect that coffee has. So you can drink a couple cups of mate and still be on the ball 3-4 hours later.
Personally I find that it gives me the same focused kind of energy as something like adderall. In fact, I've taken adderall before, so I can say firsthand that the effect is just as good, if not better. Other people I know that drink it say the same thing. Plus, it's good for you, so you can't lose.
Peace,
Bri