Conceptis Puzzles
Creator and supplier of picture-forming logic puzzles. Contains online games and those for sale from Japan.
Elite Japan Crossword
Downloadable software for solving paint by numbers puzzles in many formats, including plain black and white bitmap files. Also has a solving tutorial.
Paint by Numbers
Offers two color puzzles available to print out or solve online.
Solving Paint-by-Numbers Puzzles with Integer Prog
Article and instructions on solving puzzles.