Here's a few that I know:
dh- dear or darling husband
dc- dear or darling child or children
ds- dear or darling son
dd- dear or darling daughter
imo- in my opinion
imho- in my humble opinion
rolf- rolling on the floor
mil- mother in law
fil- father in law
sil- sister in law
bil- brother in law
nt- no text
these are just a few that are off the top of my head.
Hope it helps
Kristina