Okay, you don’t look at porn sites for the spelling or grammar, but there’s no excuse for:
Cutties - Cuties
Barley legal - Barely legal
"hampster"
I haven’t seen this one much before recently, and even now, strangely enough, I’ve only seen it here on the SDMB itself:
“I accept all awards.” This is correct.
“I accept all awards except this one.” This is also correct.
“I accept all awards accept this one.” No. No. Homophone or not, “except” is not a complicated word to grasp. It’s very basic. It’s not some moon-language word Nega-Shakespeare incorporated into the English language long ago thanks to a tiny subculture of Lunar-ethnicity English citizens. Doesn’t this “spelling” seem at all out of place?
Blagg.
Actually, this is very smart of them, assuming they also have the correct spelling somewhere. Insures that common mispellings in search engines will still hit their site.
I hate loose. Everyone seems to use it at the wrong time.
I notice that a lot of vegetarians refer to themselves as “vegitarians.”
Yes, ‘hampster’. "Definately’, too.
"Masterbation’, and all its variants.
Yes. It’s also “This person is biased and prejudiced.” Not “bias and prejudice.”
People who confuse “were” and “where” also get on my nerves (mostly because it’s a clear indication that they have never learned the rules of phonics; I am a lot more tolerant of people who confuse homophones).
I have a problem with ECT for etcetera. Just drives me Crazy!
I try not to loose my temper at teh stupid mistakes ppl make when there typing. u should relly check you’re spelling on a web sight.
It’s not an error, strictly speaking, however I cannot stand the word “orientated”. The word is “oriented”.
People who confuse “know” and “no” should be shot. One of my friends, when e-mailing me, often includes such gems as “I didn’t no what to do,” and it really does make me clench my teeth every time I see it.
I’ll also second "ect " used in place of “etc”. The signwriter where I used to work did this all the time, and seeing the fruits of her labour displayed in public was just cringeworthy.
That fancy Frenchy word for “hey presto!” is “voila!”
Not viola, which is a musical instrument.
Not walla, which is half of a city in Washington State.
Not wala, which is… well, just plain weird.
If you can’t spell it, why use it?
throws instead of “throes of passion…”
peaked instead of “piqued my curiosity…”
Spelling:
Loose instead of lose.
There/their mixups.
Worse instead of worst.
Quiet instead of quite.
Than vs then (how the &%$£ can you get that wrong??!?).
Punctuation:
Using a semi-colon instead of a colon.
But the worst of all is:
MISUSED APOSTROPHE’S. THEY DRIVE ME NUT’S. ITS GOT TO STOP!
A guy i met recently who runs a speech writing site said that 10% of people spell it that way. He includes the word speach on some of his pages so the search engines will pick it up.
Oh, and not capitalizing the word “I”.
Sorry, mogiaw 
Soo me
“per say” drives me nuts. Actually, most butchered Latin phrases annoy me.
WIErd.
Drives me NUTS.
Not a spelling error, strictly speaking, but I detest the misuse of the word “anymore”. I see it in chatrooms all the time: “Gosh, 2gud4u, you’re such a jerk anymore!” G’aaaargh!
Actually, in a real chat, that would probably be hideously butchered as: “Gosh 2gud4u ur such a jerk nemore!” Which really drives me nuts. When I’m in a chat I type all the words out completely, even if my grammar tends to be a bit colloquial. I think expressions like “ur” or “ne1” make you look so low-class.