Sudoku Fans@China site has introduced some really nice online solving features, which is rare to see at other sites.

1) Multi Player ( http://www.sudokufans.org.cn/pk/ )
Several players can solve same sudoku and see how they rank against each other. (yes, I know some other sites have this for Classic Sudoku, but not "free").
Here you can choose any of 30+ variations as well.

2) Cooperation - Solve Sudoku Together ( http://www.sudokufans.org.cn/pk2/ )
In this game, two players (partners) solve one sudoku together.


The online solving interface is neat, most of the text are in English. So lots of fun.

Be forewarned : It is bit addictive.

Registration is required, but it is free and harmless :-)

Thanks to India friends Prasanna Venkatesh Seshadri and Deb Mohanty for testing and translation.
We hope more foreigners come here and play with Chinese players. As the visitor data, we have about 10% visitors from other country per day.
If you don't like multiplay, you can also try these puzzles in integral area.
If you have a image which is rectangle or square and don't have a printer, you can upload it here, and solve it online. [Example]
All puzzles in integral area are made by my friend Muqi Shi and classic sudokus in multiplay area are made by TTHsieh. All of them are logic and interesting.
If you have any question, please leave a message here or send me an e-mail.

We made a touch input screen, you can enjoy puzzles on iPad now.