That story started off my hobby of collecting Holmes/Lovecraft pastiches! ^_^
My fanfic list. (I think I need to release a new update of that.)
And there is also the delightful Shadows over Baker Street anthology (in which “A Study in Emerald” is printed, though as I remember Gaiman also has it on his website for free as a pdf).
Anytime anybody has anything to add to my collection, please do let me know! <3