What is the best practice to name the default controller and default model?

[eluser]term25[/eluser]
I mean the one that is responsible to load your frontpage(homepage, landingpage etc.)

Do you call this controller main.php or site.php? Or frontpage.php or home.php or something else?

E.g. for the default model I am using this name: app_model.php

Is there any convention? How do you call yours?