It is one of the oldest groups of fanfic around, if not the oldest.
I highly recommend The Misadventures of Sherlock Holmes. I love that book. Someone should get on to the heirs of Ellery Queen [and all the others, Agatha Christie and August Derleth included] and see about reissuing it.
My very favorite is Richard Mallett's story about The Great Detective. Unforgettable! <3 And another Twitter user kindly recommended The Rivals of Sherlock Holmes to me. Its introduction is of great interest to Sherlockians. Particularly if you haven't delved elsewhere into the Golden Age of Detection.
If you haven't read Ellery Queen's Challenge to the Reader, you ought to. It's fun. :)
I found the book about Highly Sensitive People through the lovely MoniqueJ, who feels Sherlock is an HSP. I am becoming persuaded, since I've got farther into Chapter One. (Of course this means Moriarty probably is too -- that's a frightening thought!) I don't think Sherlock's really got Asperger's [despite John's half-joke to Lestrade; John was trying to make Greg feel better].
The Modern Misadventures of Sherlock Holmes and the Limits of Rationality. Nice take on his limits.
I'm really certain I have
More pics coming, some of which is frankly "just looking at Benedict" [natch], like this pic; although this one's got both Benedict and Martin smiling!
Benedict teases people about Sherlock, as does Mark Gatiss via a Q&A. (Don't worry, they're filming Sherlock come 2013, the boys are just messing with you!)
For fans of Andrew Scott, Radio Times just interviewed him. :)
P.S. For more GAD detective recs, see my work blog, AZ Shea, where I do bring up favorite mysteries. :)