You might be desperately searching for a facebook application to incorporate in your website. Stevetrefethen has done all his researches regarding this. It's an open source project. The way he implemented the .NET technology here is amazing. There are lot to learn from this application.
As he mentioned there is a separate Markup language(FBML) to incorporate facebook in his page. The people who are all new to FBML (like me) will get surprised by this. Just have a look.
For more details, visit http://www.stevetrefethen.com/blog/DevelopingFacebookapplicationsinCwithASPNET.aspx