WoWDB

Infamously used by Karatechop's guild <The Marvel Family> to one-shot several raid bosses during Wrath of the Lich King. Karatechop's account was permanently banned while every (I do mean every) other guild member account was suspended for 24 hours. The item was presumably changed so that there could never be a repeat of the incident.

For more in-depth information and links to other articles, read Wowpedia's article.

Incidentally, it now appears that this is the lowest item ID number still view-able in the database.