I don't have photos but I have seen tons photos of pebble used as an accent (when I was searching pebbles for my bath). I assume there will be a height difference between the subway and the pebble, which wouldn't bother me, but hope you have considered that.

I think it would look really fabulous.

here is a website I had bookmarked. Hope it helps.

Here is a link that might be useful: Pebble tile pics

Olychic, thanks for the link for photos. That was really helpful.

And Pepperidge thanks for mentioning me about the difference in height. I hadn't thought of that. One of the photos showed a pebble border with subway tile. Above and below the border they showed a trim piece which took care of the height issue. So I'll probably look for something similar.