Well UKPuzzle had sudoku, and there are some odd people who enjoy them. So I’ll gradually add some to this thread. Just the Hard, Very Hard and Mental ones though.
http://crossword.info/anaxcrosswords/sudoku001 VERY HARD
http://crossword.info/anaxcrosswords/sudoku002 HARD
http://crossword.info/anaxcrosswords/soduku003 VERY HARD