I have to tell you that I have wondered abou this too. I have some gorgeous stone media/gravel that's on the darker side with some quartz looking stuff in it and I thought hmmmm contrasting that with white pool filter sand might be just the ticket.
What I can imagine in my mind is a gorgeous golf course with all of those sand bunkers, excelpt the sand is represented in the Grass and the Gravel would be the bunkers.
I am curious how long this type of scaping would last though, does it all just mix up and become kinda blah?
To the poster who posted the pic, very nice, I suppose if the end result is that I would be very happy )