The only one I've heard of is Stay Alert military gum. I have an unopened pack on my desk at work, so I can;t comment on taste. I love the instructions though...they go sort of like this:
"Chew one piece of gum for the equivalent of a cup of coffee. If that doesn;t work, chew another piece. If that doesn;t work, chew another one. Chew no more than 5 in 3 hours" Or something like that! Hilarious.