A free program for creating and solving Su Doku puzzles.

You can use GNUDoku to challenge yourself, to compute solutions,
or to verify your own solutions.

A Su Doku puzzle is a 9x9 grid which must be filled with numbers
between 1 and 9 such that each row, column, and 3x3 square contains
all 9 numbers.

WWW: http://icculus.org/~jcspray/GNUDoku/