HoDoKu - HoDoKu is a sudoku helper written in Java and available in English and German.
Yasminoku - Sudoku game and solver totally written in DHTML.
Simple Sudoku - Freeware Sudoku Puzzle Maker and Solver
NumberDrop - A uniquely challenging math puzzle game.
nsudoku - A Sudoku game made with ncurses.
Sudoku Portable - Sudoku Portable is a an addictive puzzle game originally created in France over 100 years ago.