Not a homophone, but a misplacing of letters -- aks instead of ask. AARRGGH! Puhleez, get it right.

Another thing that drives me crazy is people who do not (or maybe simply choose not to) use appropriate punctuation and then their sentences ramble on and on with no end in sight and it really gives you a headache when you try to follow what they're saying because your eyes don't get any sort of a break in the action and are forced to read on through what might have been a valid point if they had just slowed down and put it into several more concise sentences instead of one long run-on sentence that you just don't have the time, energy or patience to sort your way through, because it's too hard to follow and you didn't really care all that much anyway.

I'm with you on that one. Our local newspaper is a shocker for it...

Herman Melville springs to mind.

I've written down the stationary/automobiles,stationery/envelopes one. Thanks. I've always struggled with those. Principal and principle are another two words easily mixed up. When I was in Primary school the princpal was also the 6th grade teacher and he taught us how to tell the difference thus: The principal is my pal. Oh, how we laughed, but I've never forgotten it.

Lol!! Bionic!

My dictionary (sorry I don't have it at hand to quote directly) lists the use of fun as an adjective as "nonstandard".