The social features connect you with up to 7 other people, share your progress in achieving fitness goals, and even send motivational messages. To do that, you set up a private account with App Cubby for data syncing and sending messages.
Health Cubby has a great online user manual complete with screenshots. Instead of tracking meals with points or calories, the app has you enter a 1 to 5 rating. Rating a meal a 1 means you put the all-you-can-eat buffet out of business, while a 5 is a low-calorie, healthy meal. You also set goals for strength, cardio and...vices! While the first two involve exercise, the third item makes you set goals to reduce the number of times you indulge in a vice. My goal is to reduce my beer drinking to one a day (yeah, right...).
I've put Health Cubby on my iPhone right next to Weight Watchers Mobile. It'll be interesting to see which app I use most often. Check the gallery below for screenshots of Health Cubby in action.