How to monetize an iPhone application

Fluid Studio has been helping a company that created an iPhone application with its public relations and marketing recently. One question has plagued me, and it seems to be pervasive in the new media arenas: the technology is way cool, but how do you make a dime on it?

Some developers build apps with the intent to “flip” them and make some quick (and relatively easy) cash.

Others hope to create a following and build a database of loyal followers and thus use this information to market other apps, products, and services. This model is similar to that of Facebook and Twitter; they are still running in the red but their followings are so huge that venture capitalists flocks to them incessantly.

Are you a developer or someone that has a plan? What is your exit strategy? What has worked for you?