The ruling bodies of Golf:

An excellent discussion forum for both the history of the rules and the current rules is hosted by a friend of this site,
The Leith Society

Probably the best book for an insight into the development of the Rules of Golf from its earliest times,
Rules of the Green, by Ken Chapman

And for almost everything else you would ever want to find on golf, visit
Thor's Golf links

For collectors of old golf equipment, books and other memorabilia, visit
Old Golf Auctions

For anyone interested in preserving the traditions of this great game,
Keepers of the Game

Golfing in France? Have a look at this fantastic place, near Grenoble