The woeful misuse of the apostrophe drives me absolutely bonkers. It's nails on a chalkboard to me to see someone write you're when they really mean your or vice versa. Who's versus whose is another good one, but I cut people some slack on that one because it's way more confusing than the previous example. More recently, I don't like the practice of adding an apostrophe to make dates plural such 1960's; I always think that something ought to belong to 1960 when I see that. Also, abbreviations with random apostrophes -- such as SAT's instead of SATs. Since so many people do these things with apostrophes, I decided to do a bit of research and find out what the actual rules are.
Turns out, I'm mostly right. The apostrophe for dates and plural abbreviations can be accepted in some places by some people, but the more proper way is to omit the apostrophe in cases of plural abbreviations and dates unless there's the potential to cause some confusion such as multiple A's -- so it's A's, not As or if there is punctuation (ex: periods) within the abbreviation. A good write-up on the rules are here. Here's another post on the same subject. And there's apparently an Apostrophe Protection Society, complete with examples of apostrophe abuse.