This is not meant to be a complete list of abbreviations on any particular subject, but simply abbreviations that I have stumbled across. Most of the abbreviations though, are from the world of computers and electronics.
AC Alternating Current
ACM Association for Computing Machinery
ADC Analog-to-Digital Converter
ADSL Asymmetric Digital Subscriber Line
AFAIK As Far As I Know
AGC Automatic Gain Control
AGP Accelerated Graphics Port
AI Artificial Intelligence
AIML Artificial Intelligence Markup Language
AIML Astronomical Instrument Markup Language
AJAX Asynchronous JavaScript and XML
ALSA Advanced Linux Sound Architecture
AM Amplitude Modulation
AML Anil's Machine Language
ANSI American National Standards Institute
API Application Programming Interface
APM Advanced Power Management
APRS Automatic Packet Reporting System
APRS Automatic Position Reporting System
APT Automatic Picture Transmission
ARM Advanced RISC Machine
ARRL American Radio Relay League
ASCII American Standard Code for Information Interchange
ASIC Application Specific Integrated Circuit
ATA AT Attachment
AVATAR Autonomous Vehicle Advanced Tactical Applications Research
BBC British Broadcasting Corporation
BBS Bulletin Board System
BBT Bad Block Table
BDM Background Debugging Mode
BIND Berkeley Internet Name Domain
BIOS Basic Input Output System
BML Bean Markup Language
BOOTP BOOTstrap Protocol
BT Bluetooth
BT British Telecom
C Capacitor
CAIDA Cooperative Association for Internet Data Analysis
CAS Calibrated airspeed
CB Citizen Band
CD Compact Disc
CERN European Organisation for Nuclear Research
CGI Common Gateway Interface
CLASS Comprehensive Large Array-data Stewardship System
CML Chemical Markup Language
CMOS Complementary Metal-Oxide Semiconductor
CMS Content Management System
CORBA Common Object Request Broker Architecture
CORS Continously Operating Reference Station
CP4E Computer Programming for Everybody
CPU Central Processing Unit
CRC Class-Responsibility-Collaboration
CRC Cyclic Redundancy Check
CRM Customer Relation Management
CSS Cascading Style Sheet
CST Central Standard Time
CVS Concurrent Versions System
CW Continuous Wave
DAB Digital Audio Broadcasting
DAC Digital-to-Analog Converter
DAML DARPA Agent Markup Language
DARPA Defense Advanced Research Projects Agency
DB Decibel
DC Direct Current
DCMI Dublin Core Metadata Initiative
DHCP Dynamic Host Configuration Protocol
DIP Dual Inline Package
DLG Directed Labelled Graph (RDF)
DMZ Demilitarised Zone
DNS Domain Name System
DOM Document Object Model
DSB Direct Sounder Broadcast
DSB Double Side Band
DSL Digital Subscriber Line
DSP Digital Signal Processor
DSS Digital Speech Standard
DTD Document Type Definition
DTV Digital Television
DV Digital Video
DVD Digital Versatile Disc
DVR Digital Voice Recorder
EAN European Article Numbering System
EAS Equivalent airspeed
EBNF Extended Backus-Naur Format
ECMWF European Centre for Medium-Range Weather Forecasts
EDI Electronic Data Interchange
EEPROM Electrically Erasable Programmable Read Only Memory
EGRS Electronic & Geodetic Ranging Satellite
EGRS Experimental Geodetic Research Satellite
EKU EUMETCast Key Unit
EMD Electromagnetic Discharge
EOF End Of File
EOL End Of Line
EPROM Erasable Programmable Read Only Memory
ER Entity-Relationship
ERCIM European Research Consortium for Informatics and Mathematics
ESA European Space Agency
ETA Estimated Time of Arrival
ESMTP Extended Simple Mail Transfer Protocol
EULA End User License Agreement
FAQ Frequently Asked Questions
FEPROM Flash Erasable Programmable Read Only Memory
FET Field Effect Transistor
FIFO First In, First Out
FM Frequency Modulation
FPU Floating-Point Unit
FTP File Transfer Protocol
FYI For Your Information
GAL Generic Array Logic
GDT Global Descriptor Table
GIF Graphical Interchange Format
GIMP GNU Image Manipulation Programme
GIOVE Galileo In-Orbit Validation Element
GML Generalised Markup Language
GMT Greenwich Meridian Time
GNU GNU is Not Unix
GOES Geostationary Operational Environmental Satellites
GPIB General Purpose Interface Bus
GPL GNU General Public License
GPS Global Positioning System
GRUB Grand Unified Bootloader
GSFC Goddard Space Flight Center
GSM Global System for Mobile Communications
GTK GIMP Toolkit
GUI Graphical User Interface
HDTV High Definition Television
HF High Frequency
HRPT High Resolution Picture Transmission
HTML HyperText Markup Language
HTTP HyperText Transfer Protocol
HZ Hertz
IANA Internet Assigned Numbers Authority
IATA International Air Transport Association
IBM International Business Machines
IC Integrated Circuit
ICE In-Circuit Emulator
ICANN Internet Corporation for Assigned Names and Numbers
IDE Integrated Development Environment
IDE Integrated Drive Electronics
IDEA International Data Encryption Algorithm
IDT Interrupt Descriptor Table
IEC International Engineering Consortium
IEEE Institute of Electrical and Electronics Engineers
IETF Internet Engineering Task Force
IMAP Internet Message Access Protocol
IMHO In My Humble Opinion
IML Instrument Markup Language
INT Integer
IP Internet Protocol
IRI Internationalised Resource Identifier
IRQ Interrupt Request
IRTF Internet Research Task Force
ISA Industry Standard Architecture
ISBN International Standard Book Number
ISDN Integrated Services Digital Network
ISOC Internet Society
ISO International Organisation for Standardisation
ISP Internet Service Provider
ISS International Space Station
IT Information Technology
ITU International Telecommunication Union
JAXP Java API for XML Processing
JESAUG Journal of Environmental Satellite Amateur Users Group
JPEG Joint Photographic Experts Group
JPG Joint Photographic Experts Group
JSP Java Server Pages
JTAG Joint Test Action Group
JVM Java Virtual Machine
KHZ Kilo Hertz
KWH Kilo Watt Hour
L Coil
LAN Local Area Network
LCC Life Cycle Costs
LCD Liquid Crystal Display
LDAP Lightweight Directory Access Protocol
LDP Linux Documentation Project
LDT Local Descriptor Table
LED Light Emitting Diode
LILO Linux Loader
LSB Least Significant Byte
LTSC Learning Technology Standards Committee (IEEE)
MAC Media Access Control
MBR Master Boot Record
MBR Minimum Bounding Rectangle
MCA Micro Channel Architecture
MDA Mail Delivery Agent
MDD Meteorological Data Distribution
MHZ Mega Hertz
MIME Multipurpose Internet Mail Extensions
MIT Massachusetts Institute of Technology
ML Meta-Language
MMU Memory Management Unit
MODEM Modulator-Demodulator
MOF Meta-Object Facility
MOSFET Metal-Oxide Semiconductor Field Effect Transistor
MPEG Moving Picture Experts Group
MSB Most Significant Byte
MSG Meteosat Second Generation
MTA Mail Transport Agent
MTBF Mean Time Between Failure
MTD Memory Technology Device
NASA National Aeronautics and Space Administration
NFS Network File System
NMOS Negative-channel Metal-Oxide Semiconductor
NOAA National Oceanographic and Atmospheric Administration
NPN Negative-Positive-Negative
NTSC National Television Standards Committee
OCLC Online Computer Library Center, Inc.
OCR Optical Character Recognition
OEM Original Equipment Manufacturer
OIG Orbital Information Group
OIL Ontology Inference Layer
OMG Object Management Group
OMT Object Modeling Technique
OOA&D Object-Oriented Analysis and Design
OOP Object-Oriented Programming
OOPSLA Object-Oriented Programming, Systems, Languages, and Applications
OPML Outline Processor Markup Language
OSC Oscillator
OSI Open Systems Interconnection
OSS Open Source Software
OWL Web Ontology Language
PAL Phase Alternation Line
PAL Programmable Array Logic
PAIS Public Affairs Information Service (OCLC)
PBM Portable Bit Map
PERL Pathologically Eclectic Rubbish Lister
PERL Practical Extraction and Report Language
PCI Peripheral Component Interconnect
PCMCIA Personal Computer Memory Card International Association
PDA Personal Digital Assistant
PDF Portable Document Format
PFC Proficiency Check
PI Processing Instruction
PIC Pilot In Command
PIC Position Independent Code
PIC Programmable Interrupt Controller
PLA Programmable Logic Array
PLD Programmable Logic Device
PLL Phase-Locked Loop
PMOS Positive-channel Metal-Oxide Semiconductor
PM Phase Modulation
PNG Portable Network Graphics
PNP Positive-Negative-Positive
POES Polar-orbiting Operational Environmental Satellite
POP Post Office Protocol
POSIX Portable Operating System Interfaces
PPP Point-to-Point Protocol
PROM Programmable Read Only Memory
PSI Published Subject Indicators
QA Quality Assurance
QC Quality Control
R Resistor
RA Right Ascension
RAID Redundant Array of Independent Disks
RAM Random Access Memory
REST Representational State Transfer
RCS Revision Control System
RDB Relational Database
RDBMS Relational Database Management Server
RDF Radio Direction Finding
RDF Resource Description Framework
RF Radio Frequency
RFC Request For Comments
RFID Radio Frequency Identification
RINEX Receiver Independent Exchange Format
RISC Reduced Instruction Set Computer
ROM Read Only Memory
RPC Remote Procedure Call
RPM Redhat Packet Manager
RSS RDF Site Summary
RSS Really Simple Syndication
RSS Resource Site Summary
RTM Read The Manual
RUP Rational Unified Process
SAN Storage Area Network
SARSAT Search & Rescue Satellite Aided Tracking
SAX Simple API for XML
SCP Secure Copy
SCR Space Charge Region
SCSI Small Computer Systems Interface
SDTV Standard Definition Television
SECAM Systeme en Couleurs a Memoire
SECOR Sequential Collation of Range
SEP Single Engine Piston
SET Secure Electronic Transaction
SEVIRI Spinning Enhanced Visible & InfraRed Imager
SGF Structured Graph Format
SGML Standard Generalised Markup Language
SHOE Simple HTML Ontology Extensions
SIG
SKU Stock Keeping Unit
SLOC Source Lines of Code
SMD Surface Mount Device
SMIL Synchronised Multimedia Integration Language
SMTP Simple Mail Transfer Protocol
S/N Signal to Noise ratio
SNMP Simple Network Managment Protocol
SOAP Simple Object Access Protocol
SPARQL SPARQL Protocol and RDF Query Language
SRID Spatial Reference Identifier
SSB Single Side Band
SSH Secure Shell
SSI Server Side Includes
SSL Secure Socket Layer
SSN Social Security Number
STN Super-Twisted Nematic (LCD)
STOL Short Take-Off and Landing
SVG Scalable Vector Graphics
SVGA Super Video Graphics Array
SW Semantic Web
TAB Tape Automated Bonding
TCL Tool Command Language
TCP Transmission Control Protocol
TFTP Trivial File Transfer Protocol
TIP TIROS Information Processor
TIROS Television Infrared Observation Satellite
TK Tool Kit
TLE Two Line Element
TMA Terminal Control Area
TMCL Topic Map Constraint Language
TMQL Topic Map Query Language
TN Twisted Nematic (LCD)
TNC Terminal Node Controller
TTY Teletype
TZ Time Zone
UAV Unmanned Aerial Vehicle
UBE Unsolicited Bulk Email
UBL Universal Business Language
UCE Unsolicited Commercial Email
UCS Universal Character Set
UDDI Universal Description, Discovery and Integration
UDP Universal Datagram Protocol
UHF Ultra High Frequency
UI User Interface
UML Unified Modeling Language
URI Uniform Resource Identifier
URL Uniform Resource Locator
URN Uniform Resource Name
USB Universal Serial Bus
UTC Universal Time Coordinated
UTF UCS Transformation Format
UUCP Unix-to-Unix Copy
V4L Video For Linux
VFO Variable Frequency Oscillator
VGA Video Graphics Array
VHF Very High Frequency
VIP Versatile Information Processor
VMOS Vertical MOSFET
VOB Video OBjects
VOX Voice-operated switch
VXML VoiceXML
W3C World Wide Web Consortium
WML Wireless Markup Language
WSDL Web Services Description Language
WWW World Wide Web
XFDL Extensible Forms Description Language
XGA Extended Graphics Array
XHTML Extensible HyperText Markup Language
XIS XML Information Set
XMI XML Metadata Interchange
XML-RPC XML Remote Procedure Call
XML Extensible Markup Language
XMLP XML Protocol
XP Extreme Programming
XSL-FO XSL-Formatting Objects
XSL Extensible Stylesheet Language
XSLT Extensible Stylesheet Language Transformation
XTM XML Topic Maps
XUL XML-based User interface Language