nelson06, they are called Lumenocks, and Cabela's have them. They are pricy. $9.99 each or a 3 pack for $27.99. They are on page 37 of the 2005 Archery catalog. I have never really been tempted to try them. I use orange nocks and orange and white vanes with white/orange fade arrow wraps and have never had a problem seeing them.
I guess they have their benefits but is a personal preferance thing. Like I said, nothing I have ever really wanted to try.