There are some sources that use LOL for "Lots of Luck". Most common usage does seem to be "Laugh Out Loud" or "Laughing Out Loud". For other abbreviations you might run across check some of the following Chat Room Dictionaries:
http://www.chat-avenue.com/abbreviations.html
http://www.cse.ucsc.edu/~shankari/abbreviations.html
http://www.a1chat-rooms.com/abb.htm
2003 Almond GT