http://wiki.sgmk-ssam.ch/wiki/Arduino_Uno_R3_as_HID
www.usb.org/developers/hidpage/Hut1_12v2.pdf
http://jlbicquelet.free.fr/notes/claviers.php
Arduino UNO R3
Write code in batch and vbscript. This script download an another program who shit in your screen. duuuh suuurry...
Become a real spy (or pain in the ass) and add some buttons to adapt the mapping of keyboard (qwerty, azerty et cetera...).