Hey everyone -- check out
sudoku100.com. It solves sudokus, and only displays as much of the solution as you tell it to.
It's really useful if you're having a lot of trouble getting off the ground with a particularly difficult sudoku. Just enter your puzzle, click on the squares you want to know, and go!
It's also handy if you make a mistake. With sudoku100, you can locate your error quickly and get on with the puzzling!