I use one of these:
Pyrotect Neck Collar
The velcro is worn out and needs to be replaced, but I have about 50k miles on it. It actually supports the weight of the helmet a little, so now it feels funny to ride without it. I have a string attaching the front strap of the neck ring to the waist of my jacket, as wind pushes the ring back on my neck. If the ring is pushed back, it makes it a little harder to look over my shoulder. With the string in place, I can look over my should just as easily as I can without the neck ring at all.
There are a couple of things to consider with the ring. Wind noise is somewhat reduced. Your neck stays warmer and does not get sunburnt. The things are foam inside, so you can drench them in water on hot days.
The neck support in Stephan's link looks very nice.