Here be spoilers! Lots. Seriously, not only should you not click if you don't want to hear these, but some of the initials are NOT going to stand for the person you think they are.
But I'm masking versus accidental spoilers.
Also, if the ending of Sign made you sad, these links may make it worse. FEELS alert.
Especially for acafanmom's The fine line between comedy and pathos.
Here's a roundup of meta on The Sign of Three at knackorcraft. 8)
Sherlock and J----- from welovethebeekeeper
Sherlock as the b---- from bbcatemysoul
The Sign of Three visually tells us from alabellecreation
Can we talk about this? from hold-my-tea (my response to this: Ohhh, Molly, YES!)
Why Sherlock behaves like a psychopath but isn't one from The Norwood Builder
A study in Sherlock (from ivyblossom) will almost definitely make you cry whether you ship or not. Trust me. Awwwwwwww.
ALSO: Master list of metas (for all of S3) by knackorcraft, with sub-grouping by character, category, episode, etc.