After my post above about the French translation, I figured I'd go and take a look at the various other translations of his name (courtesy of Wikipedia). Note to anyone intending to write a massively successful series translated into dozens of languages: beware the anagrams! (And also the abbreviations that are meant to be mysterious, but that's for a later book...)

Dutch: Marten Asmodom Vilijn (from "Mijn naam is Voldemort"

Nice work with the last name, which while not an actual Dutch word (and hence not too obvious) reminds one of English and French "vil(l)ain". The middle name is somewhat unfortunate (although it has a vague Old Testament-demon feel to it, cf. WoT's Asmodean), but there's worse in other languages. I actually think this is the most original and creative solution in any language that I've seen.

French: Tom Elvis Jedusor (from "Je suis Voldemort"

They kept the first name, following the pattern of utter inconsistency in their treatment of names (see my other post). I'm not sure what to make of the last name (phonetically it sounds like "J'ai du sort", but that would mean "I have fate" which is rather nonsensical, so maybe it's a coincidence), but it's the middle name that is gold. Elvis lives, indeed.

Spanish: unchanged in some editions (boo!), Tom Sorvolo Ryddle (from: "Soy Lord Voldemort" in others

They were lucky that they could keep the changes as minimal as they did, since "I am" is equally short in Spanish, and they had a Y to replace the I in the last name. Obviously the meaning of the last name is lost in translation, but then I don't think there's any language where they managed to keep it, not with the heavy constraint of the anagram. (Edit: yes, there is: Russian has his last name as "Rebus", apparently.)

German: Tom Vorlost Riddle (from "Ist Lord Voldemort"

Cheaters. Total cheaters. They'd have had a fair bit more trouble with "Ich bin (Lord) Voldemort". And "ist" doesn't really make any sense.

Arabic: Seems to have refrained from the complete mess that trying to do an anagram in the Semitic alphabet would have become, and just transliterated the English names (as they usually do in cases like this).

Italian: Tom Orvoloson Riddle (from "Son' io Lord Voldemort"

See Spanish - could limit their changes to the middle name, not much to comment on.

Finnish: Tom Lomen Valedro (from "Ma olen Voldemort"

Can't really comment as I know too little Finnish, but another one where they had to improvise.

Latin: Tom Mosvux Riddle (supposedly from "Sum Dux Voldemort", but that doesn't actually fit, they'd have to make it "Ruddle"

Not sure why they bothered changing the middle name if they weren't going to make the anagram fit anyway, but it's a fairly amusing middle name all the same.

Danish: Romeo G. Detlev Jr. (from: "Jeg er Voldemort"

Takes the prize for best first name by a mile. Romeo? Seriously? Detlev reminds me of Detlef Job, guitarist of the awesome German band Novalis. Cleverly done with the Jr., though.

I'll stop there, but since I just found a longer list (in the Breton Wikipedia, of all places...), I'll link it below. Looks like I could keep going on, really.