Android App for 3G, iPhone, Pocket PC

Hi Guys, I am trying to build an application that follows the same rules as my website script [login to view URL] which is a twitter train service and what it does, people will get to sign up with their twitter account and follow 20 people and then will join the train, so after they have joined, they also get a chance to show up on the train and people will follow them as well. More they follow, there is more chance of getting more followers or they also can buy VIP pass through PayPal. And then they don't have to follow any body in favore of getting followers. So I want the software to be cost free, I am not selling it so people get to download it on their phones (3G, iPhone, Pocket PC) and I want it simple and interactive frame so it is fun to work with the application and my main goal is to get people to visit my website and hopefully this way I will increase the traffic to my website. Thanks, FRED