My pet peeve is the positively rampant and likely knee-jerk use of the abbreviation for the phrase: "Laughing Out Loud."
I would estimate that it (I refuse to actually type those three letters out!) is the most overused shorthand in all the internet, if not all current writing, period. There are unfortunate numbers of people out there who will use it automatically in response to virtually any statement, particularly in chat rooms, but also in emails and posts (albeit thankfully, not much if at all here! [WHEW!]). What particularly irritates me is when it is used in response to what I perceive as a serious situation, or one which at least deserves thought in response.
I will admit to the use of SOME chat abbreviations on occasion. For the most part, I prefer to write what I think in whole words, if for no other reason than to make what I'm saying at least reasonably unambiguous. [It doesn't hurt that I type between 60-80 wpm, either.] But I have not, do not, and will not use the above-referenced abbreviation and I view those who do as both lacking in brain cells and likely losing them with each use.
meh there are plenty of situations where LOL is appropriate, in the same way emoticons are appropriate. the internet as a communication medium has progressed from a strictly 'written medium" to be an "avatar communication medium" meaning that the communication is no longer simply 'written' but pretends at real life, whereby LOL, and smileys, and frownies, and roflmao are all very appropriate. The purpose being to imitate the natural flow of speech.
In a real conversation, you don't need to take the time to completely spell out the emotion of laughter, it does the same thing in chat rooms. It's not about writing letters, it's about direct speech through the keyboard.
Language can evolve all it wants to, but as it comes to formal communication (in which I've found my aforementioned abbreviation more than once!), I communicate in whole sentences with punctuation, without exception.
I insist that too much of this "new communication" is a product of laziness and an inability or unwillingness to TYPE. I understand most if not all of it, occasionally use it, but that does NOT mean I have to participate in lackadaisical communication as a baseline means.