I think I remember seeing a few crossovers with Sherlock Holmes that had Holmes going to Hogwarts. I don't really remember seeing anything worth reading though.

 

Maybe he'll be able to solve this mystery...

 

Oh, there is a brand new one:

This great ficlet features a male!Hermione. And (s)he isn't called Hermes either:
https://forums.darklordpotter.net/showthread.php?t=22587

 

I have to admit, having read that earlier today, I laughed out loud when I saw the title behind the link.

 

Well, this isn't exactly a male!Hermione fic, because she lived most of her live in a female body, but the genderbending is still done well. Plus: The writing is damn good.

http://www.fanfiction.net/s/6685668/1/A-Switched-Chance

 

I gave it a chance. Then the horrendous nicknames began . . . and the Ron bashing.

Also, 11-year-olds don't respond to Hermione's (in Harry's body) cutting wit and devastating logic the way Draco did, they "win" by calling you a dum-dum-poopy-head and smugly smile as everyone laughs with them at you. In Draco's case, I guess he might only stoop as low as saying, "At least my mother isn't a filthy muggle."

All in all, these things made me drop it.

 

There is 'The Black Phoenix'.

Warnings: The author is inclining towards slash.

It's a dimensional travel where Hermione wakes up in the body of Sirius Black and Harry Potter wakes up in the body of Grindelwald's grandson. Dunno why the two of the best stories where Grindelwald is involved deeply are slash. It sucks.

Link: http://www.fanfiction.net/s/6125328/1/Black-Phoenix

 

What story are you talking about?