There are a lot of words that people seem to mix up all the time. A friend of mine was complaining about this the other day and I was surprised to realize how many come up pretty regularly. These are some I thought of:
cue - as in take your cue from someone
queue - a lineup
Sometimes I've come across people writing about taking a queue. Wrong kind.
borrow - I borrowed the car from Jack.
lend - I lent the car to Jack.
These get confused all the time, as in "I borrowed him my car". Drives me nuts!
peace - the absence of war
piece - a piece of something
Often I see people write that they've said their peace. In that context, it doesn't make sense. Piece is the word they're looking for.
Got any to add?