USB hosting with the mega

Projects Networking, Protocols, and Devices
4

That should be no problem, you have HID support for the USB host shield:

http://hunt.net.nz/users/darran/weblog/c6f35/Arduino_USB_Keyboard_Passthrough.html

and

http://www.circuitsathome.com/mcu/hid-support-for-usb-host-shield-library-2-0-released