As I have posted before:
There are much better ways for you to bootstrap cash injectors to your application. Applications that are ad injected tend not to preform as well as ones that are not.
Any application which you consider to be worth more than free but are afraid may cause less downloads if not paid for should at the very least have an easy way to donate. People often overlook this fact and yet many people I know, if given an application that solves there problem will donate 5 or so dollars. This may not sound like a lot but it is essentially money for nothing given that there is no reason NOT to implement this.
Another option is to see if you can bootstrap a similar application with yours. If this is done in a professional manner with the ability for the user not to install the second app then it can be a good source of income and no nasty adverts for the user to contend with.
The last option is to ask yourself if you would pay for it? Many people give away applications that people would happily pay a few dollars for. Consider a marketing campaign that says great software at a great price. Many people (Myself again) have paid for software that works nicely. Sure you can probably find a free cracked version but a lot of folks respect the fact that people should be paid.
Some examples of paid for software that is doing well is pinnicale profiler, ultramon and regex buddy. All of which I have paid for and would happily pay for a second time round.
