iPhone App For Group Accountability

This is an app that is going to be used for accountability to a group of people. Basically, you enter things you must do at specific places and specific times and the system will verify that those things are done via GPS data, some manual entry as well as photos. The system will allow the user to send only photos that are taken within the app and it will place a time date stamp on the photos so it's clear when they were taken. Users will enter things like their weight and other things on a daily basis and they will get to see graphs of how they're doing. Users will also enter what they are eating, when they're working out, how much they're working, etc. Users will be able to see how others are doing and they can compare people by graphing progress for more than one person at once. I want something very clean and user-friendly. I'm not interested in something basic that looks terrible so if you don't know how to build clean, user-friendly apps, please do not apply. Also, look at the App for LinkedIn to see the kind of look and feel I'm looking for.