http://www.cranksports.comOur Referee's association Training Director told me about this stuff. His wife got him hooked on it, she does Triathalons and stuff, and swears by it. It gives you that extra boost when you need it, and doesn't give you the caffine boost followed by a quick decline like energy drinks. I just bought a 16 pack to try them out for myself, but a lot of Referees in minor-professional hockey have been using these.
If interested, PM me for the # to sign up, you get a discount, and the guy who told me about it gets a credit.
Cheers.