You can add your Facebook application to your page tab, this will make more users for your applications but the main benefit will be promotion of your page. You can have a custom landing page for your page by adding a beautifully created application and that will lead for increased likes.
Application side preparation:
Your application should be coded such a way that it has only allowed FBML tags. Facebook restricts some tabs to be used inside Facebook. e.g. fb:like , fb:login. You will get an invalid tag error when you will add it as a tab.
Open Facebook developer page, edit your application settings.
Tab Name: Tab name you want to see on page.
Tab URL: This the URL of your server folder. Index file under the folder will get loaded as tab when tab will be clicked. This folder must be a sub folder of your application folder.
Edit URL: You can leave this field empty.
Page Side Settings:
Visit your application profile URL and click add to page.
You can have your application profile URL from developer page only.
On your application profile click add to page from left side (below profile picture)
Press “Add to Page” for your desired page.
Visit your page, Edit page from left panel. Under apps tab, for the application click “Edit Settings” for desired application.
Click add to tab.
Visit your page now. Click + symbol in tabs, type the application name, select it from result and the application will be added to the tab.
To make the tab default landing tab for your page, visit Wall tab of page. Click settings and choose from drop down “Default Landing Tab for Everyone Else:”
Hope you enjoyed doing the difficult task yourself, wishing Facebook Team will make it easy.