These are similar but appear to only work on stock nuts (not locking nuts) as well;
http://www.prestigewheel.com/Image999712c.asp#19mm%20Lug%20Bolt%20Covers
These may fit all of them, but not what I would want....
http://www.colorlugs.com/
http://www.colorlugs.com/colors.htm
I see you were on Rennlist asking as well, hard to find, huh??