Have you ever looked longingly at your mouse, noting its underutilized input device real estate? Canon has, replacing that excessive unused space with a built-in calculator in its X Mark I Mouse, announced today for folks in the US. (If you'll recall, we spent a few quality moments with this guy in Germany last year at Photokina.) The combo device provides users with both a physical ten-digit adding machine and a numeric Bluetooth 2.0 keypad, which you can use seamlessly with a variety of apps, replacing the number pad now absent on many deskt
