Check out Slider:

Yes!  It's finally here! Version 1.0!  No more "Not yet implemented" messages!

 The source is divided into a number of files:
 

Slider.java	The primary class for the puzzle - initialization, user input.
AppletFrame.java	I tried to make this somewhat generic (re-useable)
ImageCanvas.java	This came out of a tutorial*
SliderBox.java	Modeling and implementation of the physical puzzle box
SliderTile.java	and of the tiles
SliderAbout.java	The About Slider dialog (what else?)

 
* Very useful - I'm gonna put it on line.