Here are a few. There are more. I always try to mean the one that is most appropriate in the moment:
MA	Massachusetts (US postal abbreviation)
MA	Mature Audiences (TV program rating)
MA	Milliampere
MA	Mildly Amused
MA	Market America (independent entrepenurial corporation founded by James H Ridinger)
MA	Master
MA	Materials
MA	Moving Average
MA	Medical Assistance
MA	Maintenance
MA	Medical Assistant
MA	Meta Analysis
MA	Military Academy (West Point, NY)
MA	Management Accounting
MA	Microsoft Access
MA	Move Along
MA	Mannheim, Germany (license plate)
MA	Manual (welding)
MA	Mathematics
MA	Mid-Atlantic (region; various organizations)
MA	Metropolitan Area
MA	Monoclonal Antibody
MA	Manitoba
MA	Morocco (ISO country code, top level domain)
MA	Multiple Access
MA	Madagascar (Malagasy)
MA	Management Agent (metadirectory services)
MA	Martial Artist (gaming, Anarchy Online)
MA	Medicare Advantage
MA	Mexican American (classification)
MA	Management Analyst
MA	Military Applications
MA	Massive Attack (band)
MA	Maranhao (Brazil)
MA	Map Analysis
MA	Million Years (geology)
MA	Mission Accomplished
MA	Marin Academy (California)
MA	Mittelalter (German: Middle Ages)
MA	Methamphetamine
MA	Maranhão (Brazilian state)
MA	Medical Advisor
MA	Michael Alexander (jewelry)
MA	Military Attaché (US Navy)
MA	Mission Assurance (Homeland Defense)
MA	Marijuana Anonymous
MA	Maintenance Agreement
MA	Multiple Award
MA	Martha Argerich (pianist)
MA	Mechanical Advantage (machines)
MA	Management Activity
MA	Measurement and Analysis (process area; Capability Maturity Model Integration)
MA	Maanantai (Finnish: Monday)
MA	Morbid Angel (band)
MA	Master-at-Arms (military rating)
MA	Martial Artist (gaming)
MA	Maritime Administration
MA	Member Association (various organizations)
MA	Memetic Algorithm (evolutionary computing)
MA	Maleic Anhydride
MA	Management Accounts
MA	Modified Atmosphere
MA	Mental Age
MA	Marketing Authorization
MA	Mean Average (mathematics)
MA	Metropolitan Area Network
MA	Multi-Access
MA	Magister Artium (Master of Arts)
MA	Missed Abortion
MA	Multimedia Authoring
MA	Mission Area
MA	Mandelic Acid
MA	Modern Apprenticeship
MA	Mobile Armor (Gundam series)
MA	Mobile Assistant
MA	Monitoring Agency
MA	Major Arcana (Lineage 2 game armor set)
MA	Medical Attendant
MA	Mechanical Animals (Marilyn Manson album)
MA	Mission Analysis
MA	Microaneurysm (ophthalmology)
MA	Metabolic Analyzer (US NASA)
MA	Mass Analyzer
MA	Molecular Absorption
MA	Materials Analyst
MA	Missed Approach
MA	Military Assistant
MA	Moored Alongside
MA	Maintenance Action
MA	Mortuary Affairs
MA	Maître Auxiliaire (French: Adjunct Professor)
MA	Missed Appointment
MA	Medical Administrator
MA	Minnehaha Academy (Minneapolis)
MA	Motorcycling Australia
MA	Mission Assignment
MA	Masurium (element)
MA	Mobility Agent
MA	Multiple Answer
MA	Managed Availability (computing)
MA	Minor Arterial (State highway Information)
MA	Minor Actinide
MA	Maximum Allowance
MA	Margin Agreement
MA	Message Analysis
MA	Methanandamide
MA	Main Assist (Everquest)
MA	Middle Assyrian
MA	Marshalling Area
MA	Makarska, Croatia (license plate)
MA	Magnetic Amplifier
MA	Mission Abort
MA	Maintenance Administrator
MA	Master Administrator
MA	Manual Assist (nursing)
MA	Military Aircrew
MA	Maintaining Activity
MA	Management Advocate
MA	Music Ant (online guide for music software)
MA	Maître Ès Arts (French: Master of Arts)
MA	Mega Annum (one million years, geological chronology)
MA	Mobilization Assistant
MA	Merchandise Analyst (retail)
MA	Maintainability Analysis
MA	Maintenance and Adaptation (ATMF)
MA	Mobile Allocation (PCS - GSM)
MA	Manufacturing Approval
MA	Mesh Antenna
MA	Motorist Assist
MA	Machine Accountant (Naval Rating)
MA	Memory Administration
MA	MatureAsskickers (gaming clan)
MA	Mini Alert (System Sensor Sounder)
MA	Mechanical Ambush
MA	Master of Audiology
MA	Multi-Alert (system sensor brand name)
MA	MediArchive (website)
MA	Magical Alliance (gaming group)
MA	MJU Alert (Hekimian)
MA	Willys-Overland 1/4 Ton 4 X 4 Truck (1st Model of WWII Jeep)
MA	Malev Hungarian Airlines Limited - Hungary (IATA airline code)
MA	Makeshift Apathy (Michigan band))
MA	MANPRINT Assessment
MA	Multichambered Autoinjector
MA	(USN Rating) Master-At-Arms
MA	Miscible Accounting