Someday, I really must write a Mary Sue fic. Really, I must. I have all SORTS of ideas. *snerk*
And OMG, Sherlock Holmes with the One Ring is a VERY BAD IDEA. Very bad. 'Cause dude, he uses it like a cell phone, and if cell phones had appeared in our world a century early, I don't think any of would be around today because the world would have ended, except that it wouldn't, because Captain Janeway -- who's really an Immortal, complete with sword, didn't you know? -- would swoop back through time and space to save the planet from the Goa'uld. Sauron was really a Goa'uld. Yes.
(Can you tell that I've been reading really really bad crossover fanfics?)