Facebook development apps, is this doable?

Hi,
I have never developed anything on Facebook. I am running a classified ads website (ASP.NET) using on the backend a SQL Server database. We have got about 11’000 fans on our FB page where we’re publishing daily selected ads from our website.
I am investigating if there is a way to create an application allowing our fans to publish ads and to have those ads appearing on our website.
This would mean that from the FB apps reading data from a stored procedure to get some basic data such as categories and city, on publishing triggering a few stored procedure to do some validation checks and eventually write in the database the ads. Besides being published in our database the ads should appear on our wall. The cherry on the cake would be allowing our fans to choose a picture and publish it on our website but I can live without it.

Is this doable ? Can a FB apps interactuate with a SQL Server database located outside its server ?

It appears that my question was silly, wasn’t it ? Still if somebody has an answer…