Royal Naval Amateur Radio Society
Radio Officers Association
Radio Society of Great Britain
Gloucestershire County Radio Amateurs' Emergency Network
(This site has moved - link to be updated.)
Islands On The Air
British Amateur Radio Lighthouse Society
Worked All Britian
Worked All Ireland
Motorcycling Amateur Radio Club
The British Motorcyclists Federation
First Class CW Operators Club (I'm not a member, but it's an interesting site if you enjoy CW)
Other Radio Clubs and Organisations include the Cheltenham Amateur Radio Association (CARA), and the Radio Amateurs' Old Timers Association (RAOTA).
QRZ.COM callsearch
Buckmaster's World Wide Hamcall Server
Motor Sports Association
Association of Motorsport Recovery Operators
Land Rover