I just started using MyFitnessPal. It consists of a website with a diet/weight/exercise tracking tool, a forum, and smartphone apps for all the major platform.

I tried it when I first got my phone, but had trouble getting it set up. I finally tried going to the website with a regular computer and it all came together. You basically answer a bunch of questions about where you are and where you wanna go (with respect to fitness and weight and stuff), then it sets a calorie budget and (here's the cool part) you can enter food you eat by scanning the barcodes on the packaging. It knows what the barcodes map to, including nutritional data. You just confirm number of servings and BANG, the food you eat is tracked. Pretty cool. The database it uses seems to be a hybrid between a database from the food industry plus users can enter in their own food combinations and calorie counts for them. Besides the barcodes, you can also do text searches of the database for foods that are the same or similar to what you eat (so, for instance, I found a roast beef on rye with muenster, which is close enough the roast beef on rye with provalone that I had for lunch).

On the exercise side, you can enter in activities (for instance, cycling at X speed, with lots of ranges of speed), and tell it how long you did it, and it increases your calorie budget accordingly. So on the days I ride, I can eat a little more.

This has been my problem is that I haven't effectively managed how much I eat relative to how much I ride. After using this app for a day or two, it looks like this will be a pretty good tool for controlling my intake relative to exercise.

Does anyone use this or similar apps? What are your experiences?