I just read a magazine article on building successful web apps. Most important thing is to have a really fast app. Do this even if you have to fake it and make the app look like it is responsive.Make sure your apps reach out to your users with reminders. Here is a thought. Listen to what your users are saying. Then respond by adding new features to your app that wow your users.
The end goal is to make money with your app. That does not mean you have to charge for it. You can go freemium. Or you can puts ads in there. There are a lot of other options.
