In case you haven't seen it yet, there is a community for asexual Holmes fic (set in the BBC Sherlock universe). It includes this awesome story by Tuesdays with Moriarty. I highly recommend it, because it features post-retirement scenes, including Sherlock investigating the colony collapse disorder for bees. Really great!
I have tried writing an asexual Holmes story in the past, though set in the Victorian canon. It's somewhat more depressing so far, though I intend it to have a happy ending. Lately I tried to make some more progress on the fic, but remain undecided about whether to include a love triangle where Watson is tempted to "cheat" on Holmes.