This is a fascinating grid showing the sounds that animals are said to make in different languages:
Cat mewing
Danish: miav
Dutch: miauw
English: meow
Finnish: miau
French: miaou
German: miau
Greek: miaou
Hebrew: miyau
Hungarian: miau
Italian: miau
Japanese: nyan nyan/nyaa nyaa
Russian: miyau
Spanish: miao
Swedish: mjan mjan
Turkish: miyav
Urdu: meow
(via Kottke)
Update: Elias sez, "This is from the DRAE (Dictionary of the Royal Spanish Academy), where you can see that the sound of the cat in Spanish is not 'miao' but 'miau'."
Update 2: Anders sez, "The Swedish entry for how a cat sounds is also wrong, and should be 'Mjau, mjau.'"
