I really wanted to put some Monty Python and the Holy Grail quotes in about not being dead yet, but I couldn’t find a good way to do it.
Anyway, these would be abbreviations I guess, and not acronyms, but:
TLC use to be The Learning Channel.
GSN use to be Game Show Network.
The History Channel use to be…oh wait…not an abbreviation or acronym.
And I love how, apparently, for a while KFC stopped being Kentucky Fried Chicken, and then after a few years that’s what it stood for again.
The American Society for Industrial Security wanted to reflect that it had grown into a worldwide organization. The question is how to do that when the first word in your name is “American”.
Solution: ASIS International.
I think SQL was first called SEQUEL and then reduced down to just the SQL part.
I’ve done some database work and IME there’s a 50:50 split between those that read it S Q L and those that say “sequel”. “Squeel” I have never heard.
Anyway, the point for the pedants is simply the difficulty / arbitrariness of classifying it as strictly an acronym or abbreviation.
I was observing that people were adding examples that had already been given up thread, and others were just throwing in examples of abbreviations that weren’t well known – not what the OP asked. Perhaps we could just change the OP to “what are some abbreviations for things?”
No, SEQUEL stood for Structured English Query Language, but was dropped because it was a trademarked term in England. So they changed to Structured Query Language, which is abbreviated SQL.
A question about one story I have heard:
SPRINT (the telecom company) was originally Southern Pacific Railroad Internal Telegraph. It came from the telegraph & signaling wires that the railroad ran alongside its tracks, and was able to expand into the telecommunications business easily because it already land to run additional communications lines, didn’t have to worry about gaining access to the right of way across the country. So they could enter this business much faster than others.
Anyone know if this story is true?
Without looking that up, I’d say it sounds ridiculous. Still, most corporations have timelines on their sites. The Sprint history pages don’t back up the story either - they started out in 1899 as the “Brown Telephone Company”. They went through “United Utilities” and “United Telecom[munications]”, before launching the “Sprint” brand name in 1986:
Meh… Actually, it’s pretty much ‘par for the course’, after seven pages of posts, IMHO. 
Why does it sound ridiculous? It sounds perfectly plausible to me. It’s what my telecom law professor said. According to Wikipedia, Sprint was formed by a merger of several companies, one whose origins were with Brown, and one from Southern Pacific.
Good one, when was the last time you sent a telegram?
The official name of IBM is still International Business Machines Corp. The Machines may be a lot more sophisticated these days, but it’s still applicable.
Why did you begin that with “no”? That’s an elaboration on what I said 
Although we do have a bank called National Bank of Canada (Banque nationale du Canada). Ironically it’s one of the smaller chartered banks. I did once have a tourist ask me if it was the central bank, based on its name.
CIBC is still the Canadian Imperial Bank of Commerce, and they make no attempt to obscure this. The long form of the name is written in the footer of every page on their website, and it’s also used in their contracts and bank account agreements:
I haven’t watched Canadian TV since 1999, but around that time CIBC were running television ads using the long form of their name.
As others have pointed out, IBM still stands for something.
It originated as “General Motors Truck Co.” and the name was changed to “GMC Trucks.” So the C means “company.”
All it means is that some abbreviations can be either acronyms or initialisms, depending on how the speaker pronounces it. It doesn’t obviate the distinction.
CSX Rail.