Dave,
Ray has a web page with pictures and a recipe, but I don't have the URL handy.
A Ray's fly is an olive over yellow over white bucktail jobbie, with peacock herl on top and little bits of krystal flash in between each layer of bucktail. Everything is tied in at the head, on the top of the shank. The hook can be dressed in tinsel, I just do a wrap of black thread.
There's a semi-scientific reason for the yellow -- Ray swears that the fatty tissue of a bay anchovie looks yellow and translucent. The net effect is a sparse, translucent fly with subtle and natural color gradations and some eye-catching flash.
It works well in various situations because of its versatility. My own theory is that the olive and yellow are visible in low light, the yellow and white moreso in brighter clearer conditions, etc. Sparse and indistinct are the key -- it doesn't look exactly like anything, but when you see it in the water it excites all the baitfish receptors in a striper's brain.