Since creating this page I have found that there are actually 9 types of combs, the 9th being the Carnation comb. I've added this to my list. :)
1. The Single
The single comb is the most common. It is a simple straight row of spikes beginning at the bird's nostrils and sweeping back its head.
"Pearl," winner of the single comb contest, owned by elsasmom
2. The Buttercup
The buttercup comb is quite the novel headgear for poultry, and is reserved for the breed that carries its name. In appearance, the buttercup comb has a very small single comb in the center, with a larger one on either side.
3. The Pea
Pea combs often have 3 rows of "peas" side by side, although sometimes there is only 1 row. The "peas" are little bumps, usually quite uniform in shape and size. As the bird matures the comb grows, sometimes losing its neat, ordered appearance and becoming a large blob on the head.
"Louie," winner of the pea comb contest, owned by moomee56:
4. The Rose
Rose combs are usually rather flat and close to the bird's head. Sometimes it will form a point and extend further back than the rest of the comb.
"Puddin," winner of the rose comb contest, owned by shepan2:
5. The Strawberry
Strawberry combs are very similar to rose combs, except that they form no point and are not as flat. They are raised higher and sometimes resemble strawberries, hence the name.
6. The Cushion
This type is also similar to the rose comb, only cushion combs are rounded and smaller than the rose. They also have no point.
7. The V
Breeds with V combs have the appearance of little devils, with their long red "horns."
8. The Walnut
Walnut combs look almost exactly like their namesake. Big, pitted, and round, they can grow to shocking size and nearly cover their bearer's face.
"Elliot," winner of the walnut comb contest, owned by BarnGoddess01:
9. The Carnation
The Carnation comb is somewhat rare and found on the Empordanesa and Penedesenca breeds. It is a single comb with two side sprigs on either side of the back of the comb.
To be added soon: