Alphabetisms or Pseudo-acronyms?
Acronyms definitely exist on the Internet. They are used every day to make the already nearly-simultaneous electronic communication even faster. However, on a text-based system of communication, it is not necessary to actually pronounce the acronym, and in fact you never hear anyone actually use the common Internet acronyms in everyday spoken language. Therefore, the Internet acronyms need not conform to all the stipulations of acronyms in the spoken world.
From The Oxford English Dictionary:

Strictly speaking, most unpronounceable strings of letters found on the Internet are alphabetisms. An alphabetism is a an initialism pronounced with the names of the letters involved. However, how can we account for the fact that most of these initialisms are never pronounced? Reading an acronym, do people internalize each letter or do they internalize the string of letters as a whole word and associate it with the idea or action it represents? I will leave this actual experiment to someone else, but historically acronyms have shown a tendency to turn into words in an environment where they are spoken so I see no reason why alphabetisms couldn't or wouldn't do the same in a written environment.

There are natural acronyms, such as IMHO, but it is harder to determine a natural alphabetism because these initialisms are so rarely spoken. However, there are what I will call phonetic alphabetisms. These are initialisms in which each letter does not necessarily stand for the first letter of each word in the phrase but instead, when each letter is pronounced as if it were an alphabetism, is a homonym for the phrase it represents. Examples of phonetic alphabetisms are BCNU and CUL8R Therefore, B=be C=see N='in U=you, to create: "Be seein you" and L8R=l+eight+r to make "See you later."

Some of the acronyms used on the Internet originate outside the electronic world. TTFN, for example, comes to the Internet from A. A. Milne's timeless character Tigger. FYI is an import from the news and information industry. Initialisms of all types help speed up the typing process. In a medium where acronyms don't need to be pronounced, more and more are formed or invented and even new forms of initialisms are created. From even a purely mathematical stand, 4 letters is much faster to type than 10.

It is not surprising that in a general poll of a small number of Dartmouth students, 38% reported the use of initialisms. Dartmouth has it's own set of initialism like "HTH" for Home Town Honey, so the framework is already in place to receive new acronyms from outside sources. However, even then the initialisms do not seem to stray immensely into the spoken language. Instead, they sit sedately in our Blitzmail accounts.

An Acronym List A few examples to make life interesting.

New meanings for Old Words : Functional Shifts

Who is in control of what the words mean? The people who use those words every day. If a word is used in a new way and enough people continue to use it to mean that particular thing, then a new meaning will be added to its definition.

As English speakers find new and interesting ways to use their language, the meanings of words evolve and change over time. These changes are called functional shifts. On the Internet and at Dartmouth, electronic communication has drastically affected our vocabulary and connotations of many common words. "Blitz" comes immediately to mind as the word most altered by this process in the Dartmouth environs. "Sending a blitz" is not equivalent to ordering a military attack at Dartmouth. Instead, it is a very common way of saying "sending an e-mail message." The word "blitz" and derivatives thereof can be used as almost any part of speech when used in reference to the Dartmouth e-mail system. To blitz as a verb "to send electronic mail", blitzable as an adjective "available on the electronic mail system and receiving mail", and blitz as a noun with multiple meanings: "an electronic mail message," "the electronic mail system," "an account on the electronic mail system known as Blitzmail." Of course, the blitz-phenomenon is derived entirely from Blitzmail, the name of the program which most people at Dartmouth use as an electronic mail interface. For more examples of "blitz," see the Dartmouth Page.

Other, more generic and diffuse words have undergone functional shifts on the Internet. The following is a small list of new meanings for common words.
Chat
Chat has become a broader idea in the context of the Internet. Chat generally describes some kind of simultaneous conversation, in text, over the Internet. Comments are exchanged in real time which produces a textual imitation of oral exchanges. Chat-rooms, for examples, are places where many people can carry on such simultaneous communication at once.
Flame:
A flame is a verbal attack in the form of electronic text. Usually you flame someone or you are flamed in response to a pointless message or to a mass-mailing or posting. Other reasons you could be flamed are: always using upper-case for an entire message, expressing a point of view blatantly and extremely contrary to the point of view of the group involved in the conversation, just being rude in general.
Lag:
Dead time while you wait for the network to catch up to you. (1) In the case of e-mail, the time it takes between the sender's command to send the message and the moment it shows up in the recipient's in box. Obviously, we don't see much of this kind of lag with Blitzmail, but mail from other schools or commercial internet providers will sometimes take anywhere from 5 minutes to 5 hours to get through. (2) In the case of simultaneous communication over the Internet, as in conversations on a MUD, Unix-talk or X-talk, lag is the time one must wait for a response to a question or comment while the network tries to catch up with your conversation.
Post
The new twist on this word is the meaning, "an article or message sent to a newsgroup." If someone is said to post to newsgroups regularly that is to say that they compose and send a lot of messages to Internet forums.
Real Time
Simultaneous time, implying that when one party types a comment there is no time delay between the time the party sends it to the network and the time when the other party can see it on the screen.
Talk
"Let's talk" in an electronic mail message can also mean, "let's log onto our other accounts and chat." Talk is a term used for simultaneous textual communication, specifically on UNIX-based systems like coos.
Thread:
In personal or group exchanges of e-mail, the common topic and/or subject line is referred to as the thread of the conversation. Often, thread refers to the messages of the conversation itself. For example, if someone sent you mail with the subject "tristan and Arthur," you reply, placing "Re: Tristan and Arthur" in your subject line. As the conversation continues, the messages become linked by the common topic of Tristan and Arthur. You can follow a particular thread in your mail box or a news group, reading all the messages in that thread together.

"You seem very clever at explaining words, Sir," said Alice.