HoDoKu - HoDoKu is a sudoku helper written in Java and available in English and German.
Bounty Matics - Math can be fun and Bounty Matics proves it - you play as a bounty hunter that must win duels.
Yasminoku - Sudoku game and solver totally written in DHTML.
DragonBox Algebra - DragonBox Algebra 5+ - The educational game that secretly teaches you algebra.
Simple Sudoku - Freeware Sudoku Puzzle Maker and Solver
NumberDrop - A uniquely challenging math puzzle game.