There's been some talk about caffeine chewing gum lately and a lot of folks seem to like it. It does help you give that extra boost of energy and keeps you awake, which is very important sometimes and may be helpful in a survival situation.

Personally though I think there are better alternatives. In my experience nicotine provides better, longer lasting boost than caffeine and leaves you less drained afterwards once the kick is gone. That does not at all mean mean I advocate smoking (in fact I hate it) because it does far more harm than good. But there are smokeless tobacco products out there which pose much less of a health risk than cigarettes and also happen to be very effective stimulants as long as you don't abuse them.

Chewing tobacco has been quite popular with athletes and soldiers, for a reason. Unfortunately chewing or dipping tobacco usually contains a lot of dangerous side products. But this is not a problem with higher quality European dipping tobacco, Swedish snus or nicotine chewing gum. A couple of links: http://www.northerner.com/html/snus.html
http://www.northerner.com/html/snus-G_1.html

Snus in particular really helps me stay focused and alert when I'm tired, haven't had enough sleep and have to keep going. It works much better than coffee, with fewer side effects (no sudden drop of energy, less shaking etc.). Like any other stimulant you must be disciplined enough to only take it when absolutely necessary so you don't get addicted. But for those times when you're in a tight situation and need a good energy boost it will make a big difference. These days I always include a packet of dry portion snus or nicotine chewing gum in my BOB. Maybe you should consider it as well if you are looking for a similar stimulant or an alternative to caffeine.