Some Equine-related links you might find useful:

Horse Watch Sites
Horse Watch Alliance
Tracing Equines

Charities:
British Horse Society
Cheshire Horse
Equine Market Watch UK
Henry’s Helping Hoof Charity
Hillside Animal Sanctuary
Horses and Ponies Protection Association (HAPPA)
Pablo’s Horse Sanctuary
Redgate Farm Animal Sanctuary
Redwings
RSPCA
Scottish SPCA
The ARK Animal Rescue and Retirement Home
The Digglers
The Donkey Sanctuary
World Horse Welfare

Equine Information
British Equine Veterinary Association (BEVA)
The National Equine Welfare Council
Equus
Hoof Rehab
Learning About Animals
Naturally Horses

Magazines
Equestrian Life
Horse
Horse and Hound
Horse and Rider
Young Rider
Your Horse