I consider this to be the #1 Final Fantasy IV site.  It has Amano art, custom GIFs, armor guide, beastiary, character info, character skills, dropped items list, Game Genie cheat codes, tips, item guide, level listing, magic list, monster attacks, side quests, status guide, story summary, town/shop guide, full walkthrough, weapon guide, and a location guide.  There's even a comedy portion with several sections containing lots of hilarious FF4 stuff.  ^_^


Final Fantasy IV.net
This is another excellent FF4 site.  It has game info, character info, tips & secrets, and more stuff.


Subaru's Final Fantasy IV Info
Character info, game info, scans of a whole bunch of FFIV stuff, and some more stuff.