I'm in the same boat... About 2 months ago I decided to join a gym and searched the net for an iPhone app to track my workouts. What I found was Gyminee.com, which is kind of social network for keeping fit. They had the exercise tracking that I was looking for, but more importantly (it turns out) had a food tracker where users add the caloric, fat, protein, carbs, etc content for foods. You can add recipes too.
On that first day (June 20) I put in my food intake... 200g of fat! 466mg cholesterol! Super high sodium, super low potassium, hardly any fiber... That was a wakeup call, let me tell you!
I immediately began altering my diet. First thing was to remove fried foods (I probably had french fries 3-4 times a week). Then I began removing processed foods... Obviously I can't get 100% away, but I've drastically cut the amount of high-fructose anything, so I figure that's good. I also cut out soda... I'd always been drinking diet soda, so no calories to speak of, but I did a lot of research: There's not a lot of hard evidence that current diet mixtures are harmful (that could be a long conversation thread), but there's absolutely zero evidence that they're GOOD for you... So I'm on seltzer now.
30 pounds down in those two months, and I'm on track to hit my first goal (getting my BMI into 'normal' range) by Christmas (Just another 25 to go!) and then another 25 after that to get to my ideal weight, give or take. But it'll be a party at xmas!
So if anyone wants to join me on gyminee, my page is:
http://www.gyminee.com/locker_room/28927
Oh, and the iPhone interface for the site (that started it all for me):
http://www.gyminee.com/iphone/