Note: Please see a more recent post on Apple TV hacks.
ATVFiles is an application (or plugin) that lets you browse part of the ATV file system using the Apple Remote. This allows you to navigate to files that do not normally sync to the ATV. ATVFiles allows you to play any of your media (with the proper codecs installed) right from the Apple TV interface.
Note: These steps assume that you’ve already enabled SSH on your Apple TV using the procedures in this post: Hacking The Apple TV to Enable SSH.
The first step is to download the ATVFiles package. Unpack this file to the ATVFiles-1.1.0 folder. In this folder you’ll find another folder called ATVFiles.frappliance. Copy this folder (see this post for using Fugu) to the following folder on your Apple TV:
Now restart your Apple TV (hold down the ‘-‘ and ‘menu’ buttons on the Apple Remote for 6 seconds).
You should now see the addition of a Files menu item on your Apple TV. This will allow you to navigate to any files placed in your /mnt/media directory.