There is something I've been reminded I neglected to mention about using ringlight: You need a strong "hot" light, usually positioned right above or next to the ringlight, whose main purpose is to close down the pupils of the eye, and therefore reduce red eye, although you may still need to retouch. (I use a 500watt worklight from Home Depot). It also helps as a focusing aid, since most of the time when I use ringlight there isn't alot of other light in the room - usually that's the only photo light source. If you have a lot of other ambiant light in the room, you might not need it, but usually its just easier to run the hot light since it also comes close to simulating the effect of the ringlight (as much as possible) acting sort of like a modeling light. I suppose if you had other lights with modeling lights or ambiant in the room, you wouldn't need it, but I always use it, even (or especially) outdoors. Playboy photogs use ringlight as a fill light, along with a couple dozen other lights, so its not like the solo ringlight is the only way to go.
Hope that helps!
Andy Pearlman Studio