The Harry Potter Lexicon
http://www.hp-lexicon.org The most complete and amazing reference to the wonderful world of Harry Potter. Including magical spells, potions, maps, lists of wizards and all manner of magical items and devices.
Originally created in 1997 by the first Children and Technology Committee of the Association for Library Service to Children (ALSC), a division of the American Library Association. Currently maintained by the ALSC Great Web Sites Committee.