The Castlevania Dungeon Has articles, fun facts, the Castlevana timeline, character info, arsenal/history info, full game coverage, official art, fan art, official music, fan music, and fan ficion. Altogether an excellent Castlevania fan site!
Castlevania Wiki A wiki attempting to cover everything about every Castlevania game in-depth.
Castlevania: The Inverted Dungeon The counterpart to "The Castlevania Dungeon" fan site, with more reviews and several subhosted sites worth checking out.
Mr. P's Castlevania Realm An exhaustive source of Castlevania information that is most definitely worth checking out.