I'm currently studying the information at the website below. It's like "everything you always wanted to know about eating for cycling..." although the information would apply to any sport. It's been posted elsewhere, but it has helped me make sense of the gazillion products available.
http://www.naturalstrength.com/nutrition/default.asp

We used to make jokes about carrying a cooked baked potato in your jersey pocket. I'm glad to see that the PBJ has replaced this as the perfect food.