Here are a few very cool sites I found while doing research for my novel (6,364 words and counting), in no particular order except that's how they're listed in my bookmarks:

Mysterious Britain -- "a guide to the legends, folklore, myths and mysterious places of Britain"

Myth and Legend of Britain -- "Witches and warriors, ghosts and giants, dragons, demons and kings have shaped the landscape and captured the imaginations of people throughout history."

Mysterious Britain (another one) -- "Looking for something different? Want a fright? Want to hunt for sea monsters? Maybe Chostbusting?"

Historic UK -- "THE history and heritage accommodation guide to England, Scotland and Wales"

First Foot -- "the website dedicated to exposing the myth, the magic, the beliefs and the baloney, the history, mystery and blistery feet that make up every walk of Scottish life"

Caledonian Castles -- "The Web's largest collection of Scotland's castles, tower houses and fortified houses"