I also know a weird Sherlock / The Hobbit crossover. http://www.fanfiction.net/s/9400985/1/There-and-Back think of it as The hobbit in modern London with John as Bilbo. Mycroft makes appearances and I can't tell you any thing else.Sorry.
Your welcome. I hope you like them . I also know a Sherlock / Doctor Who crossover where Molly is Ten's companion instead of Martha.It's a nice AU. http://www.fanfiction.net/s/9184213/1/The-Woman-Who-Counted and it's sequelhttp://www.fanfiction.net/s/9368417/1/The-Soldier-Who-Stayed.
http://www.fanfiction.net/s/8223256/1/The-Missing-Mollies-or-Mr-Monk-and-Mr-Holmes Here you go! and the sequel http://www.fanfiction.net/s/9417228/1/The-Best-Part-or-Mr-Monk-Has-a-Guest They're very funny.wink