In the seventies of the 19th century, the American Noyes Palmer Chapman invented an unsolvable single-player game which caused some sensation because a high prize was promised to whom who would solve the problem at first. If you like to, you can read about the game's history, and visit an explanation of its unsolvability in easy-to-understand interactive examples.
There are also solvable variants - one of them is in the left of this page. Difficult sliding-puzzles can be found here as well as a hexagonal puzzle, where the tiles can be moved in six directions.
If you (and probably not the visitors of your Web-Site) like to play for your own, download a Desktop-Version (Adobe-AIR® required) for free.
The offer to download the puzzle and embed it into your page for free is still valid - independent of the time you need for solving it ;-)
Drag the tiles to restore the picture - and watch the time you need for doing this: This is the duration your visitors will stay on your site even when they are not interested in your site's content...
...don't take this too seriously. If you like to, download the puzzle and embed it into your page; it will show each time when called another picture of Claude Monet. More virtual toys with or without purpose can be found in the upper right corner ('Widgets').