As I have said many times before, the iPhone and iPod Touch has revolutionized the mobbile device not only with great features but, also because of the app store which let’s practically anyone write and application that can be distributed and or sold through the app store to the millions of users! The full developer program costs $100 to join and that gives you access to all the developer tools you need and the ability to distribute them over the apps store. If you choose to give your application out for free, then it costs you no extra money to host and distribute the application. If you charge, then Apple takes 30% of all revenue and then the developer gets to keep the other 70%.
I believe the iPhone developer program is ideal for a extra way to make some money either for someone in the workforce developing applications in their spair time or a student developing when they are not in school. If they can develop an app that people want then, they could make some good money just by better utilizing their spair time. I am not saying this is easy since you do need to learn how to program for the iPhone SDK but the good news is that Apple provides a bunch of very helpful tutorials that are able to be downloaded from the Apple developer site. If you have a good idea for an application and a decent amount of free time, consider learning how to program the iPhone it is a nice way to supplement your salery and boost your resume.