Great site with lots more links than be shown here!

Australia:

Clubs:

Geographe Radio Yachts
Lilydale Radio Yacht Club
Emu Lakes Radio Control Yacht Club

Organisations:

Australian Radio Yachting Association

Suppliers:

RMG Sailwinch   Designs, builds and sells winches.
BG Radio Yachts & Sails sells the Southern Cross IOM.
Craig Smith sells the TS-2 IOM.
Carbonicboats.com, Marbleheads, IOMs
Mirage Radio Yachts by Jeff Byerley. Mirage, Rage and Ocka IOMs
 

International:

Clubs:

York Region Marine Modellers ,Newmarket, Ontario, Canada
Windsor Model Yacht Club , Windsor, Ontario, Canada
RC Sailing Kingston , Kingston, Ontario, Canada
Lee Valley Radio Yacht Club. – UK
The Great Schooner Model Society Dedicated to the building and sailing of multi-masted sailboats.
MYSA & The London Radio Yacht ClubUK
Three Rivers Radio Yachting Club UK
 

Organisations:

R/C Sailors of Finland – A Finish model yachts Site with English version and great links page.
American Model Yachting Association  – USA Info on many classes of model yachts.
ISAF - RSD - The official site of the Radio Sailing Division.
ISAF - For the racing rules of sailing and other useful information.
The Model Yacht Sailing Association. UK
Model Yachting Association. - UK
New Zealand Radio Yachting Association.
Official International One Metre Site – USA Official International One Metre web site.
UK RC Laser Association    
North Shore Radio Yacht Squadron (NSRYS)

Help Full Hints of all sorts:

Lester Gilbert presents his views on R/C yachting. An analysis of how sails work.
A guide to racing basics by Mark Johnson.
Model Yachting Resource Centre (Dave Acree) – USA A site stuffed with many useful "How-to" articles.