Funny story: I'm a web developer and I needed to create a page where users wait on a process to complete. However, the process doesn't give any information about how far along it is, so I couldn't make an accurate progress bar. So... I made one that increments essentially randomly. However, the closer it gets to the end, the more it slows down. At 99% it stops, though it takes a while to get there.<br>It's entirely based on deception, but it works well enough; people will be glad if their results arrive faster than the progress bar predicted, so they won't complain about that. If their results take a while, though, the progress bar will still move, so they won't get the impression that the process is "stuck". Additionally, since it slows down, it gradually mentally prepares the user for a longer wait time. And even then, the results will almost always ready before the progress bar hits 99%, so users will not complain that the progress bar is inaccurate. It's a little white lie to make the experience better for the user--a rare example of deception used for good.