Although it may not be the fastest way of running a brute-force password attack on a PC BIOS, the theory of operation is interesting and novel. The Arduino board is programmed to become a virtual USB keyboard in order to enter keystrokes to the PC - and it also reads the VGA signal from the PC to determine what is being displayed on the monitor. This is done to determine what the PC is 'saying' and allows the cracker to determine its next move.
Apart from cracking BIOS passwords, this project could be modified to determine PC status - if you can predetermine what is displayed on a monitor, the Arduino can read this and do your bidding. For more information, the circuit and sketch visit the AlferSoft blog here. And we're on twitter, so follow us for news and product updates as well.
To get started with your own Arduino-embedded projects, look no further than the Freetronics LeoStick. Apart from being one of the smallest Arduino-compatibles on the market with USB, it also has an onboard RGB LED and piezo for sound and knock detection: