Harry Potter in Chinese, Japanese, and Vietnamese:
After removing rotten links, this is all that is left...
Cornelia Remi's Harry Potter Kiste - includes Character names and Chapter titles from Iceland to Estonia to Portugal to Asia, mistakes in the German edition, etc. Very interesting!
The Harry Potter Lexicon - lots of words and information.
Harry Potter Facts - all that time I was tearing my hair out, scrabbling from chapter to chapter trying to find where this character or that gadget appeared. This site has it all at your fingertips!
The Akashic Record - claims to be 'a Compendium of Lore, Onomatology, Miscellanea, and Pareidolia Relating to the Universe of Harry Potter With Commentary Esoteric and Exoteric'. the derivation of words is sometimes a bit far-fetched, but all-in-all a good resource.
Addiction: A Harry Potter Doujinshi Website A doojin-shi is (to quote) 'a Japanese fan produced comic book or a text story. They're usually very high quality and printed, not photocopied'. This is an American site but very useful if you're into this aspect of Harry Potter, as the author of this site most decidedly is!
Say-zan-sha's site (in English)
Introduction to Ly Lan, who did the Vietnamese translation. Includes biography and information on her many other works.
Learning Japanese by reading Harry Potter A blog by a person using Harry Potter to improve his Japanese - still at Book 1!
Taiwan/Hong Kong (Google is not very good for Taiwan -- too heavily infiltrated by commercial interests)
Harry Potter and the Chamber of Muggle A beautifully done site.