Bzzzspeek is site devoted to onomatopoeia. To quote from today's NY Times article:
Bzzzpeek is brilliantly and simply designed. There is virtually no text. Most of the sounds come from children. Once you enter the site, you will see a light-blue frame decorated with 29 silhouettes, mostly of animals and vehicles: a bee, a horseback rider, a duck, an owl, a cuckoo clock, a train, a police car, a car horn, a frog and so on.
Click on one of those icons, say, the duck, and you'll see nine of them lined up, each one bearing a flag representing a country. (You get to a second page of ducks by clicking on the arrow.) Choose the duck of a certain nation, say the one with the British flag, and you'll hear how children there say "quack." Then it's on to the next duck.