Is there an application for sharing wi-fi passwords?
I've searched in the iOS AppStore. I didn't find such an application. I also looked in Cydia, but no such application exists. Android's Market also said no.

Here are my thoughts on why such an application does not exist:


Sharing someone else's wifi password is an issue. He/she gave it to you so you can have internet. He/she hasn't agreed that you share it with the world. In the case of internet cafes, they have passwords so that only clients can use their wi-fi.
I spoke with an company that develops iOS applications. They said no public API exists that allows the application to get saved wi-fi passwords or to make the phone connect to a new wi-fi network.
Such an application most probably will not be accepted in the iOS AppStore (I have been told from the same company)
There are issues with implementation. How without an internet would one get the password that is needed for a concrete wi-fi network? Preload all passwords in the application? Use 3g to get that specific password?


Even though I think such an application would make people's lives a bit easier, I think there are too many problems for it to be implemented.