What are some general ideas for an iPhone app?

I want to make some extra money for the summer, so I thought I could program an iPhone app. I have plenty of experience in computers and developing, and I know of all the requirements. I just have one problem, I don't have a single idea for the app!

I don't necessarily want specific details (although if you have a request I'll look it over), I want input on what consumers generally want to buy. Please don't give me something too general like "make a game". Try to tell me basic ideas used in most popular apps. Example: "If you choose to make an RPG game, use high definition graphics. And maybe the setting could be a sandy beach with shark villains."

Give me all your ideas! I plan to start developing the app soon, so I need all the help I can get.

If you have no idea and expect others to give you specific ideas then just forget it…

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