Okay, we're a little late in covering this one; Hack A Day and Engadget beat us to it. This is a 81-Nixie tube based Sudoku board which appears to use IN-12's (based on the upside down 2 used as a 5.) There are two knobs on the board, one controls the x position and the other controls the y position of the cursor. The number pad controls the actual value of the input. Be sure to visit the site - he graciously includes the source code and schematics.