I don't know of a list, perhaps we should start one.
gg = good game
dugs = doubles game
trips = triples game
rt = real time
gl = good luck
gla = good luck all
imo = in my opinion
stack = large number of armies on one territory
territ = territory
Fort = fortify
Fort line = chain of territs held by the same player, allowing them to fort along that line to themselves or partners
Bob = Ajax bob an addon for firefox that gives you additional information about the map, (e.g. things that you could count on your own if you took the time, nothing that everyone else couldn't figure out if they took the time)
Clickies = clickable maps, an addon for firefox that allows you to click on the map to drop armies, attack and fort
auto = auto attack
dice = devil
Some ones that I use a lot
std = standard
esc = escalating
seq = sequential
drop = deploy (e.g. drop on my 5 stack)
drop also = initial setup (e.g. I got a bad drop)
fake time = casual speed or opposite of real time
Hope some of these are helpful, can anyone add a few more?