http://www.reocities.com/petsburgh/6624/ also discusses silkies and rose versus walnut combs. Excellent photos to distinguish by comb shape.
I found this excellent article on combs and wattles. Although it focuses on the non-bearded European standard, the bearded and the US standard is mentioned as well. I think it is a great article on the different combs, with lots of pictures, genetic reasons and is a great help in identification of the different combs for people starting out.
http://chickencolours.com/What Wattles-lowres.pdf