What is a good FB app

The latest thing is to invite clients to make Facebook apps. That despite the fact that FB is really not that big in Romania (I know it seems like it is, but currently HI5 still kicks FB ass with over 3 mil accounts) and that apps cannot be mass launched so they still rely on the age old concept of "okay, everyone in the agency send this to your friends list". The thing is that seldom we see a good app which you do not feel like trashing the minute you see it. So some basics of how good FB apps work:
- they are interesting enought to pass along to your list
- they renew temselves as they get passed on
- they carry a "status buzz" = meaning they are interesting to read as part of your account updates (you really really do not want to see "Bogdana was hit by a snowball from whoever")
- they carry with them the power to generate subsequent updates which are useful

As such, I think only the Bday calendar is a good FB app so far :-)