Here are some great resources for free printable sudoku puzzles:
Printable free easy, medium, and hard sudoku puzzles with solutions.
Sudoku puzzle generator that create easy, medium, hard, diabolical puzzles for free. Generates a printable PDF with solutions and pre-filled possible answers key.
Printable sudoku puzzle generator. Difficulty settings for Easy, Medium, Hard, Expert, Evil. Options to generate HTML or PDF, and with or without soloutions.