3 links
Sundial Design Program
sunshadow.co.uk
Software to design a vertical (wall mounting) sundial for walls that face up to 60 degrees away from due-south.
The British Sundial Society
sundialsoc.org.uk
Information on the society, links, beginner's pages, including simple sundial patterns and templates, online facilities to calculate hour lines for different sundial types.
The North American Sundial Society
sundials.org
Includes general information, links, a register of dials in North America, and a message board.