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.
My Tektek Environment:
[click]-->My TekTek Environment (as of 09.16.2011) Doesn't seem to be including my Sibyl's Incantation. Hrm.