This is a Deltaco mini PS2 keyboard/trackball. I've stripped it of it's former shell and built it into a LEGO-shell. I tried to keep the color scheme to black and red, but at this point, I've run out of 1x3 bricks, 1x1 bricks, and 1x1 plates in both red and black.
On the right, you can see the trackball. I've noticed that the ball is so smooth that it slips on the trackers inside, resulting in poor performance and accuracy. So I've developed a tapping technique which involves tapping the ball in the direction you want the pointer to move and then correcting back until you hit the spot. For a coming version, I will buy a mini keyboard and trackball separately and build these into the LEGO-frame. On the left, I've placed the mouse buttons. A 6b axle is suspended above the buttons, and a few technic pieces are added for ease of use.