http://www.apostropheabuse.com/
http://www.apostrophecatastrophes.com/http://www.engrish.com/
And, specifically for KOT, we have "have" versus "of:"
[Link: english.stackexchange.com]. From that site we have
I learned English as a second language, and I don't think anyone who has painstakingly learnt "I should have" and "that must have" would make this particular mistake [saying "I should of" and "that must of"]. Instead, I see this as a rather sure sign of a native English speaker.
and
It will shock many to learn that the OED has an entry for the verb ‘of’. Its etymology is given as ‘variant of HAVE (verb), arising through misapprehension of the verb (when occurring as a clitic) as showing OF (preposition)’ and it is described as non-standard.
That "misapprehension" means "you learned it by hearing and not by reading." It is non-standard because it is generally considered not to be correct.
