B is obsessed with Sudoko so I've been trying to ramp up. Here are links to two Sudoko hint/method pages
From the Daily Mail. They also have a daily download you can print out and a link to the history of the game or their involvement in it.
More from their resident expert. who also recommends a "propelling pencil" which is some Britishism I don't understand.
The Wikipedia on Sudoko.