"Here, here!" instead of "Hear, hear!"
"It's a mute point" instead of "moot point"

I think the reason "Here, here!", "mute point", "peaked", "baited breath" and "forward" bug me so much is that by using homonyms, people are losing the original sense(s) of the word(s), along with a certain richness of expression (and even understanding) which accompany the "proper" spelling(s), and I regret that loss -- even while knowing it's inevitable.