Lemme see if I remember the Gaelige pronounciation rules well enough to try that one.
“Noll-ek haw-nuh ghwaitch” right?
(The GH is IIRC like the CH in Bach except voiced.)
French is “Joyeux Noël”.
Not too bad to pronounce, considering “joie-de-vivre” and “Noel” have snuck right into the English language already.
Yesterday I put flea prevention stuff on Auggie, The Cutest Dog on the Planet ™. The whole time, I sang… “Fleas on the dog, fleas on the dog…” I don’t think I’ll ever be able to hear that song again without siging my own lyrics.
Felice means happy in Italian. So if you happen to be Italian and Spanish, Felice Navidad 
Close enough. I’d say the last word as “ditch” (and spell it duit), but there are regional variations.
Serbian: Srećan Božić. (srech-an boh-zsich. That’s zs as in Zsa Zsa Gabor)
Darn, you beat me to it. I got so far down in the thread I was sure I’d get to show off. I’ll do the transliteration anyway, and that way I’ll feel I’ve contributed something.
“Jwoy-OO No-EL”
(Actually, the “eux” is somewhere between “oo” and “ew”)
Literally translated: “Joyous Christmas”
Japanese: Merii kurisumasu. (Try saying it aloud.)
Except that in Italian, it’s actually “Buon Natale.” (although “felice” does mean “happy” in Italian; it’s just not used in this particular seasonal greeting).
Mele kalikimaka!
(Hawaiian)
Indonesion - Selamat Hari Natal
Hawaiian - Melle Kelikimaka
Woohoo! Simulpost for the Hawaiian!
We need to get busy and tell 15,000 websites they have it misspelled. 
http://www.google.com/search?sourceid=navclient&ie=UTF-8&q=felice+navidad
Japanese is fun that way!
But if “felice” were a Spanish word, it’d be pronounced fe-lee-say, not fe-leess. 
I’m not a Finn. I learned to say Merry Christmas from the Finnish exchange student in high school.
If you’re a Finn, I stand corrected. If you’re not, then I guess it’s a draw.