Recent updates to Apple's Airport firmware enable you to use Back to My Mac to remotely access files stored on(or a hard disk attached to with 802.11n) from a Mac running OS X Leopard. The device's disk will appear on your Mac in the Shared section of the Finder sidebar when you're connected to the internet, and you can treat it as a personal remote file server, dragging files to and from it as needed.
To setup a device, Open AirPort Utility on your Mac, click Manual Setup, then click Advanced in the toolbar and select MobileMe. Enter your MobileMe member name and password and click update. For more detailed instructions download the Back to My Mac User's Guide.