I've often seen 'rest bite' on a forum for carers of people with dementia. There's some logic to it - the poor things are desperate for a 'bite' of rest.
Nearly all the above-mentioned in pps drive me mad, too.
IMO it's pretty shocking how many people don't know the difference between it's/its, your/you're, there/their/they're, etc. - all perfectly simple basics that should have been sorted out in primary school.
At a higher level, the number of supposedly reasonably educated people who don't know the difference between disinterested/uninterested, discreet/discreet, among others, does often raise my eyebrows too.
Oh, and advice/advise!!!
I used to have a colleague who always said, 'I done it,' 'I rung her,' etc. I would never have dreamt of correcting her, but at the same time she was very conscious of her lack of education and I really think she'd have liked to know.
I've only ever corrected somebody online once - after that person had corrected someone else, and made a basic mistake in their own post!
Pots and kettles....