Not abbreviations, mind you (“LOL” is covered in a different entry), but rather the use of a single letter or number, on its on, in place of a word which sounds like that single letter or number. U, R, B, 2, 1 … all of that crap.
While it has always bothered me when people have used this kind of chat-shorthand, it is a little more understandable when people have an unavoidable, hard-coded, character limit (a la Twitter). With the rise of phones boasting full QWERTY keyboards, there is little reason to continue being lazy in your text messages.
The one place I refuse to tolerate this, however, is in Instant Messaging conversations. More and more people are able, and willing, to IM on their mobile devices, and nearly all such devices have some method of input that no longer requires this lazy chat-shorthand that so many are *so* fond of using, but there is *no* excuse for carrying it over to computer-based IM conversations.
Any amount of time you *think* you’re saving by saying, “will u b there” instead of “will you be there” is wasted by my sitting at the other end fuming and fighting the reflex urge to delete you from my buddy list.