The Secret Garden Fan Fiction Society :: More than likely the best Secret Garden fan-site out there, complete with fanfiction, fanart and topical discussions. 5 stars!
Come to my Garden :: A site with information on the musical version of the Secret Garden.
Fanfiction.net :: A link to the Secret Garden fanfiction category on ff.net.
Kate Maberly's Flight 29 :: a site devoted to the actress Kate Maberly, the star of the 1993 film adaption of the Secret Garden.
SparkNotes: the Secret Garden :: a thorough examination of the Secret Garden. Very interesting for lovers of the book - and, of course, recommended for anyone writing an essay ;)