Ring flashes can produce great lighting for portraits, either by themselves or part of a multi-lighting scheme. Expo Imaging recently released the Ray Flash: The Ring Flash Adapter that "creates a three-dimensional shadow-wrapped look around the subject. Because ring flash light originates from a circle around the lens, it produces a virtually shadowless look on the front of your subject, while producing a soft even shadow around the edges."
To put this new device through its paces, Strobist recently published a full review of the Ray Flash. The bottom line?
"...if you are mobile -- and especially if you like the TTL thing -- you have to give the Ray Flash strong consideration. And this design clearly took a lot of time and effort to produce. Not to mention a some very expensive mold design."
"For the people for whom it makes economic sense, the cost will be returned many times."
"I suspect that the Ray Flash will be a hit with the hipster wedding shooter crowd. It takes up almost no room in the bag, then you just slip it on when you wanna do the funky bride shot. You can do it at each wedding -- it's always new to them, right? This thing could make some cool reception pix, too, if you are into that kind of thing."
If you can afford the $300 price tag, Ray Flash is available directly from Expo Imaging