This is the main one, and I'm not sure if any others exist, nowadays:
http://www.realmsofthehaunting.com/

You can even find back-ups of the long-gone official ROTH web sites there as well, thanks to the diligence of the site owner.

I would be wary of spoilers, however.

What else... reviews?
http://www.gamerankings.com/pc/198432-realms-of-the-haunting/
http://pc.mobygames.com/game/dos/realms-of-the-haunting

Tales From The Tower Wiki

I haven't looked around much but the references bit is quite interesting, definitely worth checking out.

Spoilers, obviously.