Hart to Hart by Meredy
Images, sounds, free downloads, and electronic postcards based on the series.
http://www.meredy.com/hart2hart/

Hart To Hart Online: Keeping the Harts Alive
Episode guide, downloads, pictures, cast profiles (including Freeway the dog), and information on the Harts' lifestyle.
http://www.geocities.com/harttohartonline

Hart To Hart Online
Includes behind the scenes information, current TV listings, cast information, downloads, and episode guides for the series.
http://hartsonline.users.btopenworld.com/

Hart Home
Includes cast biographies, episode guide, production details, candid and episode photos, and interviews.
http://users.hunterlink.net.au/~lmcvd/harts/harthome.htm

TV Tome: Hart to Hart
Episode guide with cast and crew information.
http://www.tv.com/hart-to-hart/show/1314/summary.html

Yahoo! Groups: Hart 2 Hart
Discussion and chat about the series, the actors, and related memorabilia. [Yahoo! registration required.]
http://tv.groups.yahoo.com/group/hart2hart/

Hart to Hart Episode Guide
Includes credits and other details for the various segments.
http://www.geocities.com/Hollywood/9821/harts.txt

IMDb: Hart to Hart
Cast, crew, and production information, as well as viewer comments.
http://us.imdb.com/title/tt0078622/

Yahoo! Groups : Hart to Hart
Mailing list and photo sharing. [Yahoo! registration required.]
http://tv.groups.yahoo.com/group/harttohart/