Here is some:
AP - Assistants to the President, mission president's top missionaries
BIC- Born In the Covenant (parents had been sealed in the temple prior to your birth)
BIL - Brother-in-Law
BIC - Born in Covenant
BKP - Boyd K Packer
BoA - Book of Abraham
BoM - Book of Mormon
BP - Branch President
BY - Brigham Young
BYC - Bishop's Youth Council
BYU - Brigham Young University
CES - Church Education System
CHI - Church Handbook of Instruction
CK - Celestial Kingdom, where God lives and all Mormon believers strive to reach
COB - Church Office Building
COJCOLDS - Church of Jesus Christ of Latter-Day Saints
COP - Corporation of the President
CTR - Choose the Right, a mormon saying and common sybmol on rings worn by Mormons
D&C - Doctrine and Covenants
DH - Dear Husband
DL - District Leader, responsible for 3 or 4 sets of missionaries
EFY - Especially For Youth
EQ - Elder's Quorum
ET - Ezra Taft Benson
FAIR - Foundation for Apologetic Information & Research, apologetic organization
FARMS - Foundation for Ancient Research and Mormon Studies, Church apologetic organization
FHE - Family Home Evening
FIL - Father-in-Law
FPR = Faith Promoting Rumor
FS - Fast Sunday
FTM - Fast and Testimony Meeting
F&T - alternate for fast and testimony meeting
GA - General Authority
GBH - Gordon B. Hinckley
HC - High Council
HP - High Priest
HT - Home Teacher
ISPART - Institute for the Study and Preservation of Ancient Religious Texts, church apologetic organization
JM - Jack Mormon
JoD - Journal of Discources
JS - Joseph Smith
JST - Joseph Smith Translation
JW - Jehovah's Witnesses (or Jdub)
LDS - Latter-Day-Saint
MD -
MIL - Mother-in-Law
MINO Mormon In Name Only
MMM - Mountain Meadows Massacre
MP - Mission President (militare police

)
MTC - Missionary Training Center
PGP -
PEC - Presthod Executive Comitee
RM - Returned Missionary
RS - Relief Society
SITT -
SSP - SundaySchool President
STU -
TBM -
QUAD- Quadruple Combination of the Bible
ZL - Zone Leader
YM - Young Men
YW - Young Women
YWP - Young Women's President