There are many different types of bantam ducks, the biggest variety is the call ducks though, which come in a VERY wide variety of colors! 
I myself raise a few, and I own a bantam call duck yahoo group where there are many others who raise colors I do not even have!
Call ducks as grace mentioned were used by hunters years ago, the females are very vocal, mainly when they see you coming, when mine are ready to be out of the pen, ready for there daily pool change, hungry, or looking for a friend. But they do quack in my opinion more then the larger ducks I have had, Rouens, Indian Runners, Khaki Campbells etc.
The calls are the smaller of the bantam ducks. 
Calls come in colors like, Gray, (which many people call "Bantam Call Mallard", which is wrong, its just "Gray Call" who gets the "Mallard" label on them because they are colored just like the wild Mallards.) Dusky, (which is a darker in color Gray), Snowy, Apricot Silver, Buff, Khaki, Penciled, White, Silver, Pastel, Blue Fawn, Self Blue, Blue Bib, Black Bib, Black & White Magpie, Blue & White Magpie,  Black, Self Black, Butterscotch, Spot, Fwn & White, Pied, Yellow Belly, Chocolate, Blue Butterscotch,you get the picture there are alot of different call duck colors!
Silky Call Ducks 
Black East Indies (pure black, beautiful green sheen!)
Blue East Indies
Aussie Spotted
And others I am not thinking of past midnight!
Good luck on your search, there are ALOT of call breeders out there!