I was looking for some caustics texture on Google (mostly discussions of it populated the top of the list) and came across a generator for it. I think it’s pretty nice.
Check it out: http://www.lysator.liu.se/~kand/caustics/
All the renders that come out are tileable.
It doesn’t seem to do all that well when you set the image size so its ratio doesn’t come out 1:1. Still, I think it could be an invaluable tool, especially for those who want to make a nice underwater scene or something involving a outdoor swimming pool (just to name a few examples :))
You can render an animation sequence as well.