How to animate a water ripple?

Hi all,

Does anyone have a good method for animating a water ripple over a bitmap image? I’m looking for something similar to the technique offered here but this tutorial is a bit out-dated: http://www.freehandsource.com/_test/ripple.html

I have a feeling someone may have developed something better using Flash 8 so I thought I would ask the kirupa heads.

Any ideas are welcome!

thanks