Dear all,
I recently picked up a trial version of FilterForge at http://www.filterforge.com. This tool is amazing and equally amazing are the things others have already done with it. It does take getting used to and, especially, it takes you to learn to look a certain way at real live textures so you can break them down and rebuild them in FiIterForge. If you manage to do so you will be able to easily make variants and tailor them to your needs. All in high or low res and all seamable.
The catch is a learning curve and the fact that depending on the version you want it's pricey. The upbeat: great texture made by clever people, al ready to use and endless possibilities.
My trial has ended, but I will install a second one on my laptop soon. I have one texture in their library called: sand ripple. I intend to make it more realistic and more customisable.
Check it out. Maybe some of us who can and want to afford such a buy can specialice in using it.