I have not used but can definitely see a good chance for some saltwater applications. Autumn issue of Fyltyer magazine has an article on a similar product, at least some ties involving these or a type of.
I agree with Bob, they look similar to Popovic's Fleye Foils. The Fisheadz look a bit more realistic in my opinion, especially the eyes. Here is a thread is started last year regarding the foils. I enhanced the eye with a stick on eye and highlighted the gill with a red sharpie. http://www.washingtonflyfishing.com/forum/index.php?threads/fleye-foils.77818/#post-744887 SF