Yes it is a great site.

Things that fitday can help you with:
1) Make sure you are getting enough calories for your Basal metabolism rate.
2) Make sure you are getting the vitamins and minerals you need.
3) Make sure you are getting the right amounds of fat/carbs/protein and fiber.
4) Determine how much your exercise is burning in calories.
5) Set goals for weight among other things.
6) Track your progress.
7) Figure out which foods fit best into this way of eating.
8) Even keep a journal there.

I'm sure I'm missing some, but those are the high lights.