S&S or Sns = sew and show (there's also buy and show, knit and show, dye and show, etc.)
RTW = ready to wear
SOAA = Sisterhood of Amity Artisans (a group of Amity mamas who sell on eBay,
click here for more information.)
OT = off topic
FS = for sale
ISO = in search of
MM = Malden Mills (name brand fleece) or sometimes Michael Miller (fabric brand)
SG = stash game (there's usually a sticky post at the top of the forum when it's going on, it has more details in it)