- Seeing their, there, and they're used interchangeably.
- Ditto your, you're (and yore?, well maybe not)
- People who don't know the difference between "ten times more than" and "ten times as much as".
and this one, I noticed today:
My wife suggests Christmas letters which don't include spell-check. And newscasters who refer to the police as cops, or refuse to refer to POTUS by his title.