Sudoku
http://www.freedailysudoku.net/
http://www.delano.k12.mn.us/sitepages/pid1612.php
http://sudoku.com.au/
http://www.schooltimegames.com/Logic/Sudoku.html
http://www.websudoku.com/
http://www.sudoku-puzzles.net/
http://puzzles.about.com/library/sudoku/blsudoku_tutorial01.htm
http://www.sudogo.com/
http://www.krazydad.com/sudoku/
http://www.pdfpad.com/sudoku/
http://www.number-logic.com/
http://www.sudokuonline.us/free_sudoku_puzzles.php
http://www.strictlysudoku.com/more-sudoku.php
http://www.sudokucollection.com/sp/Sudokux.html
http://www.squidoo.com/sudoku-puzzles/