A good iPhone/Android or any app which is developed with good features and released with out a good marketing strategy  may fail, because you throw your app in to a store which is completely occupied and there is no way your application gets attention from users until you do marketing. And here are some of them which you can follow:

1.Choose a unique, catchy name for your app so that it can be found within the app store and Google searches.

2.There a lots of iPhone app review sites out there. Get in touch with them and submit a “press release” about your application.

3.You can promote your app in interactive ads contained within other iPhone apps.

4.Add a feature in your App that lets the user to share your app itunes URL to his friends through Mail, SMS. Set the default text in them that speaks about your app .

5. You can let the user share his views on your app in Twitter using a twitter update feature.

6. Promote it through LinkedIn, facebook, your blogs, Myspace and where ever the cyberspace you travel.

7. Create a separate shiny website that is meant for your app. provide screenshots of your app, video tutorials on usage and features of your app.

8. Participate in developer forums like stackoverflow, iphonedevsdk and promote your app.

9. Promote your app through  you mail – signature(provide a URL to App store).

Bye !!!