Well saying advertising is general/vague. Advertising IS how you market an app (or anything) haha. But here are a few quick ways I would say: create a facebook group/fan page for your app, invite everyone. Create squidoo pages on your app, any kind of social web2.0 site about it. Also social bookmark it like crazy (digg, reddit, delicious etc)
If it is a cool app that might get some press coverage then send out a press release about it, not just to papers/magazines but also to the multitude of websites that write about about apps.
If your app is good and you have a huge friends list so your app can market easily among friends via news feeds.
Yeah if it's actually a good app, just use it and share it on facebook, then ask your friends to do the same.
Getting all your friends to add it and then get their friends to add / discuss it and it should spread around.
kalki, do as they say, promoti it throu your friends. And make them promote it too. Also you can pay magazine or any other media publisher to write a review of your application - this helps a lot too.
You could build a WP site aimed at marketing and describing the app. Basically a small dedicated site to it.
hey, so what is exactly about app of facebook? It is a script or just a blog page ? i dont get what the feedback here saying about!