Note: This is NOT my Tool. I simply found it buried in the web, and figured others may find it useful.
Recently I found myself in need of a texture that looked like the effect caused by light reflecting on surfaces from the refraction of light in water. Also known as caustics you tend to see this natural occurrence on sunny days near medium to large bodies of water which have buildings or bridges nearby.
You see a reflection of the light bouncing off water on these structures typically on the lower/under side.
I found it quite difficult to generate a good looking image in photoshop so I went on the hunt for a tool or shader which would do the heavy lifting for me.
Thanks to polycount and the Wayback machine I was able to find a tool called Caustics Generator offered under GPL
The tool is capable of rendering high quality super sampled caustics with a plethora of options to tweak and shape the effect. It also allows us to render an animation of typical caustics movement.
Probably one of the most important features to note is that the generated images tile in both directions making animation or scrolling super easy.