Lots of people have tried to "complete" the canon. Here is Leslie Klinger's entry of "apocrypha" annotated in the style of the other volumes in the Sherlock Holmes Reference Library. Here his annotations seem a bit more lackadaisical, but still interesting and informative. The apocrypha consists of:

"The Field Bazaar" - a necessity, as it is a short little story by Doyle himself.
"How Watson Learned the Trick" - ditto, the short little comedy for the Queen's Dollhouse library.

These two are necessities.

Included too:

"The Man with the Watches" and "The Lost Special" - two mystery stories published by Doyle during the Great Hiatus, with the mention of a "celebrated reasoner" that is likely Holmes. These two are often included in Sherlockian apocrypha.

"The Stonor Case" is a terrible retelling by Doyle of the good story "The Speckled Band."
"The Crown Diamond" is an even more terrible play by Doyle, which led to the terrible story "Mazarin Stone."

"The Tall Man: A Plot for a Sherlock Holmes Story" is just that, a rough outline for a plot found in Doyle's papers after his death. Did he write it? Or was it sent to him like "The Case of the Man Who Was Wanted"? It's interesting, but a question mark.

Then there is the abomination of abominations:

"Angels of Darkness" - it was never meant to see the light of day, and it should never have. Vaguely like A Study in Scarlet's Mormon story, it has a weird Watson and silly Victorian morals and racist caricatures. It's terrible.

The sum is that Doyle was a good short story writer but a terrible dramatist. I don't know why "Sherlock Holmes: A Drama in Four Acts" wasn't included, nor the essays: "To An Undiscerning Critic"; "Some Personalia about Mr. Sherlock Holmes"; "The Truth About Sherlock Holmes"; "Mr. Sherlock Holmes to His Readers"; or "How I Made My List." Still, it is worth it for the annotations of "The Field Bazaar"; "How Watson Learned the Trick"; "The Man with the Watches"; and "The Lost Special." The first two SHOULD be included in the canon, no reason they shouldn't be; the latter two should be counted as apocrypha. The plays, to get all Sherlockian, were abominations written by the Literary Agent and not Watson. ( )