Lewis Jaffe, on his blog Confessions of a Bookplate Junkie, has a few mystery-related ones posted:
• E. V. and Laura Vanderstoep's bookplates with fingerprints
• S. Davis Levin's Conan Doyle Collection
• Sherlock Holmes-related bookplates here and here from bookseller-publisher Helan Halbach
• One for Muriel Clark Corby with a raven, which seems Poe-inspired to me.
• Arthur Conan Doyle's bookplate
• H. P. Lovecraft's bookplate
• Erle Stanley Gardner bookplates
And there's also the "Insane Department" at Philadelphia Hospital.
As I'm a Noel Coward fan, be sure to check out Sir Noel's bookplate.
About the image: Sherlockian Bookplates by William E. Butler, published by Primrose Hill Press