If you like playing Soduku, then the Touch screen hand-held Soduku should definitely be in your  pocket.

Available from Think Geek for US $19.99, the hand-held Soduku machine features a whooping 835 puzzles, 4 levels of difficulties, a game timer, auto-save and auto-off and a stylus to select the squares and numbers. Works with 2 AAA batteries and is available @ Think Geek