Is there any Perl module that helps translating things into ASCII in a reliable way?
In all seriousness, I agree to a large extent with what the others have said. If you have to do this automatically (without getting a romanized version from the user), the transliteration method is going to need to be language-specific.
For instance, for Japanese you might check out Lingua::JA::Hepburn::Passport. It doesn't appear to support kanji, but I'm not sure it's possible to automatically romanize kanji, since most of them have at least half a dozen different readings. The same character might romanize to "mei" in one name, "myo" or "myou" in another name, "min" in another, "a" in another, "aka" in another, "aki" in another (this is a real example). If you can't get furigana (pronunciation guide characters, usually kana) from the user, names are going to get romanized very incorrectly.