make money with your iphone

I'm late to the game... apparently this has been going on for a couple of years now. I just downloaded FieldAgent and GoSpotCheck because I have the old iPhone 3. EasyShift needs iOS 4.3, and GigWalk needs iOS 5.0. Owning a smartphone is expensive, and if we can offset this by using these free apps to make money. I'm currently using FieldAgent, but it often crashes because there's a lot of traffic for it. A little competition never hurt anyone:)