The computer program most people swear by is Calorie King. You can go to CalorieKing - Diet and weight loss. Calorie Counter and more. I believe they have a pay service. I have tried looking up things on there for free nad have not been overly impressed.
I have yet to find an application for my Instinct which would be nice. I'm not sure about iPhone.
I've started carrying a book with me. You can find a variety of different ones in bookstores, but tehy will have nutritional info for a variety of generic and name brand foods. That has helped me and as I get more comfortable with it I find I don't need it as often.